Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1849 insertions, 0 deletions

diff --git a/servo/components/style/values/specified/length.rs b/servo/components/style/values/specified/length.rs
new file mode 100644
index 0000000000..0afca293d0
--- /dev/null
+++ b/servo/components/style/values/specified/length.rs
@@ -0,0 +1,1849 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+//! [Length values][length].
+//!
+//! [length]: https://drafts.csswg.org/css-values/#lengths
+
+use super::{AllowQuirks, Number, Percentage, ToComputedValue};
+use crate::font_metrics::{FontMetrics, FontMetricsOrientation};
+use crate::parser::{Parse, ParserContext};
+use crate::values::computed::{self, CSSPixelLength, Context};
+use crate::values::generics::length as generics;
+use crate::values::generics::length::{
+    GenericLengthOrNumber, GenericLengthPercentageOrNormal, GenericMaxSize, GenericSize,
+};
+use crate::values::generics::NonNegative;
+use crate::values::specified::calc::{self, CalcNode};
+use crate::values::specified::NonNegativeNumber;
+use crate::values::CSSFloat;
+use crate::{Zero, ZeroNoPercent};
+use app_units::Au;
+use cssparser::{Parser, Token};
+use std::cmp;
+use std::fmt::{self, Write};
+use style_traits::values::specified::AllowedNumericType;
+use style_traits::{CssWriter, ParseError, SpecifiedValueInfo, StyleParseErrorKind, ToCss};
+
+pub use super::image::Image;
+pub use super::image::{EndingShape as GradientEndingShape, Gradient};
+pub use crate::values::specified::calc::CalcLengthPercentage;
+
+/// Number of pixels per inch
+pub const PX_PER_IN: CSSFloat = 96.;
+/// Number of pixels per centimeter
+pub const PX_PER_CM: CSSFloat = PX_PER_IN / 2.54;
+/// Number of pixels per millimeter
+pub const PX_PER_MM: CSSFloat = PX_PER_IN / 25.4;
+/// Number of pixels per quarter
+pub const PX_PER_Q: CSSFloat = PX_PER_MM / 4.;
+/// Number of pixels per point
+pub const PX_PER_PT: CSSFloat = PX_PER_IN / 72.;
+/// Number of pixels per pica
+pub const PX_PER_PC: CSSFloat = PX_PER_PT * 12.;
+
+/// A font relative length.
+#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToCss, ToShmem)]
+pub enum FontRelativeLength {
+    /// A "em" value: https://drafts.csswg.org/css-values/#em
+    #[css(dimension)]
+    Em(CSSFloat),
+    /// A "ex" value: https://drafts.csswg.org/css-values/#ex
+    #[css(dimension)]
+    Ex(CSSFloat),
+    /// A "ch" value: https://drafts.csswg.org/css-values/#ch
+    #[css(dimension)]
+    Ch(CSSFloat),
+    /// A "cap" value: https://drafts.csswg.org/css-values/#cap
+    #[css(dimension)]
+    Cap(CSSFloat),
+    /// An "ic" value: https://drafts.csswg.org/css-values/#ic
+    #[css(dimension)]
+    Ic(CSSFloat),
+    /// A "rem" value: https://drafts.csswg.org/css-values/#rem
+    #[css(dimension)]
+    Rem(CSSFloat),
+}
+
+/// A source to resolve font-relative units against
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum FontBaseSize {
+    /// Use the font-size of the current element.
+    CurrentStyle,
+    /// Use the inherited font-size.
+    InheritedStyle,
+}
+
+impl FontBaseSize {
+    /// Calculate the actual size for a given context
+    pub fn resolve(&self, context: &Context) -> computed::FontSize {
+        match *self {
+            Self::CurrentStyle => context.style().get_font().clone_font_size(),
+            Self::InheritedStyle => context.style().get_parent_font().clone_font_size(),
+        }
+    }
+}
+
+impl FontRelativeLength {
+    /// Return the unitless, raw value.
+    fn unitless_value(&self) -> CSSFloat {
+        match *self {
+            Self::Em(v) | Self::Ex(v) | Self::Ch(v) | Self::Cap(v) | Self::Ic(v) | Self::Rem(v) => {
+                v
+            },
+        }
+    }
+
+    // Return the unit, as a string.
+    fn unit(&self) -> &'static str {
+        match *self {
+            Self::Em(_) => "em",
+            Self::Ex(_) => "ex",
+            Self::Ch(_) => "ch",
+            Self::Cap(_) => "cap",
+            Self::Ic(_) => "ic",
+            Self::Rem(_) => "rem",
+        }
+    }
+
+    fn try_op<O>(&self, other: &Self, op: O) -> Result<Self, ()>
+    where
+        O: Fn(f32, f32) -> f32,
+    {
+        use self::FontRelativeLength::*;
+
+        if std::mem::discriminant(self) != std::mem::discriminant(other) {
+            return Err(());
+        }
+
+        Ok(match (self, other) {
+            (&Em(one), &Em(other)) => Em(op(one, other)),
+            (&Ex(one), &Ex(other)) => Ex(op(one, other)),
+            (&Ch(one), &Ch(other)) => Ch(op(one, other)),
+            (&Cap(one), &Cap(other)) => Cap(op(one, other)),
+            (&Ic(one), &Ic(other)) => Ic(op(one, other)),
+            (&Rem(one), &Rem(other)) => Rem(op(one, other)),
+            // See https://github.com/rust-lang/rust/issues/68867. rustc isn't
+            // able to figure it own on its own so we help.
+            _ => unsafe {
+                match *self {
+                    Em(..) | Ex(..) | Ch(..) | Cap(..) | Ic(..) | Rem(..) => {},
+                }
+                debug_unreachable!("Forgot to handle unit in try_op()")
+            },
+        })
+    }
+
+    fn map(&self, mut op: impl FnMut(f32) -> f32) -> Self {
+        match self {
+            Self::Em(x) => Self::Em(op(*x)),
+            Self::Ex(x) => Self::Ex(op(*x)),
+            Self::Ch(x) => Self::Ch(op(*x)),
+            Self::Cap(x) => Self::Cap(op(*x)),
+            Self::Ic(x) => Self::Ic(op(*x)),
+            Self::Rem(x) => Self::Rem(op(*x)),
+        }
+    }
+
+    /// Computes the font-relative length.
+    pub fn to_computed_value(
+        &self,
+        context: &Context,
+        base_size: FontBaseSize,
+    ) -> computed::Length {
+        let (reference_size, length) = self.reference_font_size_and_length(context, base_size);
+        (reference_size * length).finite()
+    }
+
+    /// Return reference font size.
+    ///
+    /// We use the base_size flag to pass a different size for computing
+    /// font-size and unconstrained font-size.
+    ///
+    /// This returns a pair, the first one is the reference font size, and the
+    /// second one is the unpacked relative length.
+    fn reference_font_size_and_length(
+        &self,
+        context: &Context,
+        base_size: FontBaseSize,
+    ) -> (computed::Length, CSSFloat) {
+        fn query_font_metrics(
+            context: &Context,
+            base_size: FontBaseSize,
+            orientation: FontMetricsOrientation,
+        ) -> FontMetrics {
+            let retrieve_math_scales = false;
+            context.query_font_metrics(base_size, orientation, retrieve_math_scales)
+        }
+
+        let reference_font_size = base_size.resolve(context);
+        match *self {
+            Self::Em(length) => {
+                if context.for_non_inherited_property.is_some() {
+                    if base_size == FontBaseSize::CurrentStyle {
+                        context
+                            .rule_cache_conditions
+                            .borrow_mut()
+                            .set_font_size_dependency(reference_font_size.computed_size);
+                    }
+                }
+
+                (reference_font_size.computed_size(), length)
+            },
+            Self::Ex(length) => {
+                // The x-height is an intrinsically horizontal metric.
+                let metrics =
+                    query_font_metrics(context, base_size, FontMetricsOrientation::Horizontal);
+                let reference_size = metrics.x_height.unwrap_or_else(|| {
+                    // https://drafts.csswg.org/css-values/#ex
+                    //
+                    //     In the cases where it is impossible or impractical to
+                    //     determine the x-height, a value of 0.5em must be
+                    //     assumed.
+                    //
+                    // (But note we use 0.5em of the used, not computed
+                    // font-size)
+                    reference_font_size.used_size() * 0.5
+                });
+                (reference_size, length)
+            },
+            Self::Ch(length) => {
+                // https://drafts.csswg.org/css-values/#ch:
+                //
+                //     Equal to the used advance measure of the “0” (ZERO,
+                //     U+0030) glyph in the font used to render it. (The advance
+                //     measure of a glyph is its advance width or height,
+                //     whichever is in the inline axis of the element.)
+                //
+                let metrics = query_font_metrics(
+                    context,
+                    base_size,
+                    FontMetricsOrientation::MatchContextPreferHorizontal,
+                );
+                let reference_size = metrics.zero_advance_measure.unwrap_or_else(|| {
+                    // https://drafts.csswg.org/css-values/#ch
+                    //
+                    //     In the cases where it is impossible or impractical to
+                    //     determine the measure of the “0” glyph, it must be
+                    //     assumed to be 0.5em wide by 1em tall. Thus, the ch
+                    //     unit falls back to 0.5em in the general case, and to
+                    //     1em when it would be typeset upright (i.e.
+                    //     writing-mode is vertical-rl or vertical-lr and
+                    //     text-orientation is upright).
+                    //
+                    // Same caveat about computed vs. used font-size applies
+                    // above.
+                    let wm = context.style().writing_mode;
+                    if wm.is_vertical() && wm.is_upright() {
+                        reference_font_size.used_size()
+                    } else {
+                        reference_font_size.used_size() * 0.5
+                    }
+                });
+                (reference_size, length)
+            },
+            Self::Cap(length) => {
+                let metrics =
+                    query_font_metrics(context, base_size, FontMetricsOrientation::Horizontal);
+                let reference_size = metrics.cap_height.unwrap_or_else(|| {
+                    // https://drafts.csswg.org/css-values/#cap
+                    //
+                    //     In the cases where it is impossible or impractical to
+                    //     determine the cap-height, the font’s ascent must be
+                    //     used.
+                    //
+                    metrics.ascent
+                });
+                (reference_size, length)
+            },
+            Self::Ic(length) => {
+                let metrics = query_font_metrics(
+                    context,
+                    base_size,
+                    FontMetricsOrientation::MatchContextPreferVertical,
+                );
+                let reference_size = metrics.ic_width.unwrap_or_else(|| {
+                    // https://drafts.csswg.org/css-values/#ic
+                    //
+                    //     In the cases where it is impossible or impractical to
+                    //     determine the ideographic advance measure, it must be
+                    //     assumed to be 1em.
+                    //
+                    // Same caveat about computed vs. used as for other
+                    // metric-dependent units.
+                    reference_font_size.used_size()
+                });
+                (reference_size, length)
+            },
+            Self::Rem(length) => {
+                // https://drafts.csswg.org/css-values/#rem:
+                //
+                //     When specified on the font-size property of the root
+                //     element, the rem units refer to the property's initial
+                //     value.
+                //
+                let reference_size = if context.builder.is_root_element || context.in_media_query {
+                    reference_font_size.computed_size()
+                } else {
+                    context.device().root_font_size()
+                };
+                (reference_size, length)
+            },
+        }
+    }
+}
+
+/// https://drafts.csswg.org/css-values/#viewport-variants
+pub enum ViewportVariant {
+    /// https://drafts.csswg.org/css-values/#ua-default-viewport-size
+    UADefault,
+    /// https://drafts.csswg.org/css-values/#small-viewport-percentage-units
+    Small,
+    /// https://drafts.csswg.org/css-values/#large-viewport-percentage-units
+    Large,
+    /// https://drafts.csswg.org/css-values/#dynamic-viewport-percentage-units
+    Dynamic,
+}
+
+/// https://drafts.csswg.org/css-values/#viewport-relative-units
+#[derive(PartialEq)]
+enum ViewportUnit {
+    /// *vw units.
+    Vw,
+    /// *vh units.
+    Vh,
+    /// *vmin units.
+    Vmin,
+    /// *vmax units.
+    Vmax,
+    /// *vb units.
+    Vb,
+    /// *vi units.
+    Vi,
+}
+
+/// A viewport-relative length.
+///
+/// <https://drafts.csswg.org/css-values/#viewport-relative-lengths>
+#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToCss, ToShmem)]
+pub enum ViewportPercentageLength {
+    /// <https://drafts.csswg.org/css-values/#valdef-length-vw>
+    #[css(dimension)]
+    Vw(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-svw>
+    #[css(dimension)]
+    Svw(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-lvw>
+    #[css(dimension)]
+    Lvw(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-dvw>
+    #[css(dimension)]
+    Dvw(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-vh>
+    #[css(dimension)]
+    Vh(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-svh>
+    #[css(dimension)]
+    Svh(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-lvh>
+    #[css(dimension)]
+    Lvh(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-dvh>
+    #[css(dimension)]
+    Dvh(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-vmin>
+    #[css(dimension)]
+    Vmin(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-svmin>
+    #[css(dimension)]
+    Svmin(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-lvmin>
+    #[css(dimension)]
+    Lvmin(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-dvmin>
+    #[css(dimension)]
+    Dvmin(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-vmax>
+    #[css(dimension)]
+    Vmax(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-svmax>
+    #[css(dimension)]
+    Svmax(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-lvmax>
+    #[css(dimension)]
+    Lvmax(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-dvmax>
+    #[css(dimension)]
+    Dvmax(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-vb>
+    #[css(dimension)]
+    Vb(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-svb>
+    #[css(dimension)]
+    Svb(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-lvb>
+    #[css(dimension)]
+    Lvb(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-dvb>
+    #[css(dimension)]
+    Dvb(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-vi>
+    #[css(dimension)]
+    Vi(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-svi>
+    #[css(dimension)]
+    Svi(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-lvi>
+    #[css(dimension)]
+    Lvi(CSSFloat),
+    /// <https://drafts.csswg.org/css-values/#valdef-length-dvi>
+    #[css(dimension)]
+    Dvi(CSSFloat),
+}
+
+impl ViewportPercentageLength {
+    /// Return the unitless, raw value.
+    fn unitless_value(&self) -> CSSFloat {
+        self.unpack().2
+    }
+
+    // Return the unit, as a string.
+    fn unit(&self) -> &'static str {
+        match *self {
+            Self::Vw(_) => "vw",
+            Self::Lvw(_) => "lvw",
+            Self::Svw(_) => "svw",
+            Self::Dvw(_) => "dvw",
+            Self::Vh(_) => "vh",
+            Self::Svh(_) => "svh",
+            Self::Lvh(_) => "lvh",
+            Self::Dvh(_) => "dvh",
+            Self::Vmin(_) => "vmin",
+            Self::Svmin(_) => "svmin",
+            Self::Lvmin(_) => "lvmin",
+            Self::Dvmin(_) => "dvmin",
+            Self::Vmax(_) => "vmax",
+            Self::Svmax(_) => "svmax",
+            Self::Lvmax(_) => "lvmax",
+            Self::Dvmax(_) => "dvmax",
+            Self::Vb(_) => "vb",
+            Self::Svb(_) => "svb",
+            Self::Lvb(_) => "lvb",
+            Self::Dvb(_) => "dvb",
+            Self::Vi(_) => "vi",
+            Self::Svi(_) => "svi",
+            Self::Lvi(_) => "lvi",
+            Self::Dvi(_) => "dvi",
+        }
+    }
+
+    fn unpack(&self) -> (ViewportVariant, ViewportUnit, CSSFloat) {
+        match *self {
+            Self::Vw(v) => (ViewportVariant::UADefault, ViewportUnit::Vw, v),
+            Self::Svw(v) => (ViewportVariant::Small, ViewportUnit::Vw, v),
+            Self::Lvw(v) => (ViewportVariant::Large, ViewportUnit::Vw, v),
+            Self::Dvw(v) => (ViewportVariant::Dynamic, ViewportUnit::Vw, v),
+            Self::Vh(v) => (ViewportVariant::UADefault, ViewportUnit::Vh, v),
+            Self::Svh(v) => (ViewportVariant::Small, ViewportUnit::Vh, v),
+            Self::Lvh(v) => (ViewportVariant::Large, ViewportUnit::Vh, v),
+            Self::Dvh(v) => (ViewportVariant::Dynamic, ViewportUnit::Vh, v),
+            Self::Vmin(v) => (ViewportVariant::UADefault, ViewportUnit::Vmin, v),
+            Self::Svmin(v) => (ViewportVariant::Small, ViewportUnit::Vmin, v),
+            Self::Lvmin(v) => (ViewportVariant::Large, ViewportUnit::Vmin, v),
+            Self::Dvmin(v) => (ViewportVariant::Dynamic, ViewportUnit::Vmin, v),
+            Self::Vmax(v) => (ViewportVariant::UADefault, ViewportUnit::Vmax, v),
+            Self::Svmax(v) => (ViewportVariant::Small, ViewportUnit::Vmax, v),
+            Self::Lvmax(v) => (ViewportVariant::Large, ViewportUnit::Vmax, v),
+            Self::Dvmax(v) => (ViewportVariant::Dynamic, ViewportUnit::Vmax, v),
+            Self::Vb(v) => (ViewportVariant::UADefault, ViewportUnit::Vb, v),
+            Self::Svb(v) => (ViewportVariant::Small, ViewportUnit::Vb, v),
+            Self::Lvb(v) => (ViewportVariant::Large, ViewportUnit::Vb, v),
+            Self::Dvb(v) => (ViewportVariant::Dynamic, ViewportUnit::Vb, v),
+            Self::Vi(v) => (ViewportVariant::UADefault, ViewportUnit::Vi, v),
+            Self::Svi(v) => (ViewportVariant::Small, ViewportUnit::Vi, v),
+            Self::Lvi(v) => (ViewportVariant::Large, ViewportUnit::Vi, v),
+            Self::Dvi(v) => (ViewportVariant::Dynamic, ViewportUnit::Vi, v),
+        }
+    }
+
+    fn try_op<O>(&self, other: &Self, op: O) -> Result<Self, ()>
+    where
+        O: Fn(f32, f32) -> f32,
+    {
+        use self::ViewportPercentageLength::*;
+
+        if std::mem::discriminant(self) != std::mem::discriminant(other) {
+            return Err(());
+        }
+
+        Ok(match (self, other) {
+            (&Vw(one), &Vw(other)) => Vw(op(one, other)),
+            (&Svw(one), &Svw(other)) => Svw(op(one, other)),
+            (&Lvw(one), &Lvw(other)) => Lvw(op(one, other)),
+            (&Dvw(one), &Dvw(other)) => Dvw(op(one, other)),
+            (&Vh(one), &Vh(other)) => Vh(op(one, other)),
+            (&Svh(one), &Svh(other)) => Svh(op(one, other)),
+            (&Lvh(one), &Lvh(other)) => Lvh(op(one, other)),
+            (&Dvh(one), &Dvh(other)) => Dvh(op(one, other)),
+            (&Vmin(one), &Vmin(other)) => Vmin(op(one, other)),
+            (&Svmin(one), &Svmin(other)) => Svmin(op(one, other)),
+            (&Lvmin(one), &Lvmin(other)) => Lvmin(op(one, other)),
+            (&Dvmin(one), &Dvmin(other)) => Dvmin(op(one, other)),
+            (&Vmax(one), &Vmax(other)) => Vmax(op(one, other)),
+            (&Svmax(one), &Svmax(other)) => Svmax(op(one, other)),
+            (&Lvmax(one), &Lvmax(other)) => Lvmax(op(one, other)),
+            (&Dvmax(one), &Dvmax(other)) => Dvmax(op(one, other)),
+            (&Vb(one), &Vb(other)) => Vb(op(one, other)),
+            (&Svb(one), &Svb(other)) => Svb(op(one, other)),
+            (&Lvb(one), &Lvb(other)) => Lvb(op(one, other)),
+            (&Dvb(one), &Dvb(other)) => Dvb(op(one, other)),
+            (&Vi(one), &Vi(other)) => Vi(op(one, other)),
+            (&Svi(one), &Svi(other)) => Svi(op(one, other)),
+            (&Lvi(one), &Lvi(other)) => Lvi(op(one, other)),
+            (&Dvi(one), &Dvi(other)) => Dvi(op(one, other)),
+            // See https://github.com/rust-lang/rust/issues/68867. rustc isn't
+            // able to figure it own on its own so we help.
+            _ => unsafe {
+                match *self {
+                    Vw(..) | Svw(..) | Lvw(..) | Dvw(..) | Vh(..) | Svh(..) | Lvh(..) |
+                    Dvh(..) | Vmin(..) | Svmin(..) | Lvmin(..) | Dvmin(..) | Vmax(..) |
+                    Svmax(..) | Lvmax(..) | Dvmax(..) | Vb(..) | Svb(..) | Lvb(..) | Dvb(..) |
+                    Vi(..) | Svi(..) | Lvi(..) | Dvi(..) => {},
+                }
+                debug_unreachable!("Forgot to handle unit in try_op()")
+            },
+        })
+    }
+
+    fn map(&self, mut op: impl FnMut(f32) -> f32) -> Self {
+        match self {
+            Self::Vw(x) => Self::Vw(op(*x)),
+            Self::Svw(x) => Self::Svw(op(*x)),
+            Self::Lvw(x) => Self::Lvw(op(*x)),
+            Self::Dvw(x) => Self::Dvw(op(*x)),
+            Self::Vh(x) => Self::Vh(op(*x)),
+            Self::Svh(x) => Self::Svh(op(*x)),
+            Self::Lvh(x) => Self::Lvh(op(*x)),
+            Self::Dvh(x) => Self::Dvh(op(*x)),
+            Self::Vmin(x) => Self::Vmin(op(*x)),
+            Self::Svmin(x) => Self::Svmin(op(*x)),
+            Self::Lvmin(x) => Self::Lvmin(op(*x)),
+            Self::Dvmin(x) => Self::Dvmin(op(*x)),
+            Self::Vmax(x) => Self::Vmax(op(*x)),
+            Self::Svmax(x) => Self::Svmax(op(*x)),
+            Self::Lvmax(x) => Self::Lvmax(op(*x)),
+            Self::Dvmax(x) => Self::Dvmax(op(*x)),
+            Self::Vb(x) => Self::Vb(op(*x)),
+            Self::Svb(x) => Self::Svb(op(*x)),
+            Self::Lvb(x) => Self::Lvb(op(*x)),
+            Self::Dvb(x) => Self::Dvb(op(*x)),
+            Self::Vi(x) => Self::Vi(op(*x)),
+            Self::Svi(x) => Self::Svi(op(*x)),
+            Self::Lvi(x) => Self::Lvi(op(*x)),
+            Self::Dvi(x) => Self::Dvi(op(*x)),
+        }
+    }
+
+    /// Computes the given viewport-relative length for the given viewport size.
+    pub fn to_computed_value(&self, context: &Context) -> CSSPixelLength {
+        let (variant, unit, factor) = self.unpack();
+        let size = context.viewport_size_for_viewport_unit_resolution(variant);
+        let length = match unit {
+            ViewportUnit::Vw => size.width,
+            ViewportUnit::Vh => size.height,
+            ViewportUnit::Vmin => cmp::min(size.width, size.height),
+            ViewportUnit::Vmax => cmp::max(size.width, size.height),
+            ViewportUnit::Vi | ViewportUnit::Vb => {
+                context
+                    .rule_cache_conditions
+                    .borrow_mut()
+                    .set_writing_mode_dependency(context.builder.writing_mode);
+                if (unit == ViewportUnit::Vb) == context.style().writing_mode.is_vertical() {
+                    size.width
+                } else {
+                    size.height
+                }
+            },
+        };
+
+        // FIXME: Bug 1396535, we need to fix the extremely small viewport length for transform.
+        // See bug 989802. We truncate so that adding multiple viewport units
+        // that add up to 100 does not overflow due to rounding differences
+        let trunc_scaled = ((length.0 as f64) * factor as f64 / 100.).trunc();
+        Au::from_f64_au(if trunc_scaled.is_nan() {
+            0.0f64
+        } else {
+            trunc_scaled
+        })
+        .into()
+    }
+}
+
+/// HTML5 "character width", as defined in HTML5 § 14.5.4.
+#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToCss, ToShmem)]
+pub struct CharacterWidth(pub i32);
+
+impl CharacterWidth {
+    /// Computes the given character width.
+    pub fn to_computed_value(&self, reference_font_size: computed::Length) -> computed::Length {
+        // This applies the *converting a character width to pixels* algorithm
+        // as specified in HTML5 § 14.5.4.
+        //
+        // TODO(pcwalton): Find these from the font.
+        let average_advance = reference_font_size * 0.5;
+        let max_advance = reference_font_size;
+        (average_advance * (self.0 as CSSFloat - 1.0) + max_advance).finite()
+    }
+}
+
+/// Represents an absolute length with its unit
+#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToCss, ToShmem)]
+pub enum AbsoluteLength {
+    /// An absolute length in pixels (px)
+    #[css(dimension)]
+    Px(CSSFloat),
+    /// An absolute length in inches (in)
+    #[css(dimension)]
+    In(CSSFloat),
+    /// An absolute length in centimeters (cm)
+    #[css(dimension)]
+    Cm(CSSFloat),
+    /// An absolute length in millimeters (mm)
+    #[css(dimension)]
+    Mm(CSSFloat),
+    /// An absolute length in quarter-millimeters (q)
+    #[css(dimension)]
+    Q(CSSFloat),
+    /// An absolute length in points (pt)
+    #[css(dimension)]
+    Pt(CSSFloat),
+    /// An absolute length in pica (pc)
+    #[css(dimension)]
+    Pc(CSSFloat),
+}
+
+impl AbsoluteLength {
+    /// Return the unitless, raw value.
+    fn unitless_value(&self) -> CSSFloat {
+        match *self {
+            Self::Px(v) |
+            Self::In(v) |
+            Self::Cm(v) |
+            Self::Mm(v) |
+            Self::Q(v) |
+            Self::Pt(v) |
+            Self::Pc(v) => v,
+        }
+    }
+
+    // Return the unit, as a string.
+    fn unit(&self) -> &'static str {
+        match *self {
+            Self::Px(_) => "px",
+            Self::In(_) => "in",
+            Self::Cm(_) => "cm",
+            Self::Mm(_) => "mm",
+            Self::Q(_) => "q",
+            Self::Pt(_) => "pt",
+            Self::Pc(_) => "pc",
+        }
+    }
+
+    /// Convert this into a pixel value.
+    #[inline]
+    pub fn to_px(&self) -> CSSFloat {
+        match *self {
+            Self::Px(value) => value,
+            Self::In(value) => value * PX_PER_IN,
+            Self::Cm(value) => value * PX_PER_CM,
+            Self::Mm(value) => value * PX_PER_MM,
+            Self::Q(value) => value * PX_PER_Q,
+            Self::Pt(value) => value * PX_PER_PT,
+            Self::Pc(value) => value * PX_PER_PC,
+        }
+    }
+
+    fn try_op<O>(&self, other: &Self, op: O) -> Result<Self, ()>
+    where
+        O: Fn(f32, f32) -> f32,
+    {
+        Ok(Self::Px(op(self.to_px(), other.to_px())))
+    }
+
+    fn map(&self, mut op: impl FnMut(f32) -> f32) -> Self {
+        Self::Px(op(self.to_px()))
+    }
+}
+
+impl ToComputedValue for AbsoluteLength {
+    type ComputedValue = CSSPixelLength;
+
+    fn to_computed_value(&self, _: &Context) -> Self::ComputedValue {
+        CSSPixelLength::new(self.to_px()).finite()
+    }
+
+    fn from_computed_value(computed: &Self::ComputedValue) -> Self {
+        Self::Px(computed.px())
+    }
+}
+
+impl PartialOrd for AbsoluteLength {
+    fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
+        self.to_px().partial_cmp(&other.to_px())
+    }
+}
+
+/// A container query length.
+///
+/// <https://drafts.csswg.org/css-contain-3/#container-lengths>
+#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToCss, ToShmem)]
+pub enum ContainerRelativeLength {
+    /// 1% of query container's width
+    #[css(dimension)]
+    Cqw(CSSFloat),
+    /// 1% of query container's height
+    #[css(dimension)]
+    Cqh(CSSFloat),
+    /// 1% of query container's inline size
+    #[css(dimension)]
+    Cqi(CSSFloat),
+    /// 1% of query container's block size
+    #[css(dimension)]
+    Cqb(CSSFloat),
+    /// The smaller value of `cqi` or `cqb`
+    #[css(dimension)]
+    Cqmin(CSSFloat),
+    /// The larger value of `cqi` or `cqb`
+    #[css(dimension)]
+    Cqmax(CSSFloat),
+}
+
+impl ContainerRelativeLength {
+    fn unitless_value(&self) -> CSSFloat {
+        match *self {
+            Self::Cqw(v) |
+            Self::Cqh(v) |
+            Self::Cqi(v) |
+            Self::Cqb(v) |
+            Self::Cqmin(v) |
+            Self::Cqmax(v) => v,
+        }
+    }
+
+    // Return the unit, as a string.
+    fn unit(&self) -> &'static str {
+        match *self {
+            Self::Cqw(_) => "cqw",
+            Self::Cqh(_) => "cqh",
+            Self::Cqi(_) => "cqi",
+            Self::Cqb(_) => "cqb",
+            Self::Cqmin(_) => "cqmin",
+            Self::Cqmax(_) => "cqmax",
+        }
+    }
+
+    pub(crate) fn try_op<O>(&self, other: &Self, op: O) -> Result<Self, ()>
+    where
+        O: Fn(f32, f32) -> f32,
+    {
+        use self::ContainerRelativeLength::*;
+
+        if std::mem::discriminant(self) != std::mem::discriminant(other) {
+            return Err(());
+        }
+
+        Ok(match (self, other) {
+            (&Cqw(one), &Cqw(other)) => Cqw(op(one, other)),
+            (&Cqh(one), &Cqh(other)) => Cqh(op(one, other)),
+            (&Cqi(one), &Cqi(other)) => Cqi(op(one, other)),
+            (&Cqb(one), &Cqb(other)) => Cqb(op(one, other)),
+            (&Cqmin(one), &Cqmin(other)) => Cqmin(op(one, other)),
+            (&Cqmax(one), &Cqmax(other)) => Cqmax(op(one, other)),
+
+            // See https://github.com/rust-lang/rust/issues/68867, then
+            // https://github.com/rust-lang/rust/pull/95161. rustc isn't
+            // able to figure it own on its own so we help.
+            _ => unsafe {
+                match *self {
+                    Cqw(..) | Cqh(..) | Cqi(..) | Cqb(..) | Cqmin(..) | Cqmax(..) => {},
+                }
+                debug_unreachable!("Forgot to handle unit in try_op()")
+            },
+        })
+    }
+
+    pub(crate) fn map(&self, mut op: impl FnMut(f32) -> f32) -> Self {
+        match self {
+            Self::Cqw(x) => Self::Cqw(op(*x)),
+            Self::Cqh(x) => Self::Cqh(op(*x)),
+            Self::Cqi(x) => Self::Cqi(op(*x)),
+            Self::Cqb(x) => Self::Cqb(op(*x)),
+            Self::Cqmin(x) => Self::Cqmin(op(*x)),
+            Self::Cqmax(x) => Self::Cqmax(op(*x)),
+        }
+    }
+
+    /// Computes the given container-relative length.
+    pub fn to_computed_value(&self, context: &Context) -> CSSPixelLength {
+        if context.for_non_inherited_property.is_some() {
+            context.rule_cache_conditions.borrow_mut().set_uncacheable();
+        }
+        let size = context.get_container_size_query();
+        let (factor, container_length) = match *self {
+            Self::Cqw(v) => (v, size.get_container_width(context)),
+            Self::Cqh(v) => (v, size.get_container_height(context)),
+            Self::Cqi(v) => (v, size.get_container_inline_size(context)),
+            Self::Cqb(v) => (v, size.get_container_block_size(context)),
+            Self::Cqmin(v) => (
+                v,
+                cmp::min(
+                    size.get_container_inline_size(context),
+                    size.get_container_block_size(context),
+                ),
+            ),
+            Self::Cqmax(v) => (
+                v,
+                cmp::max(
+                    size.get_container_inline_size(context),
+                    size.get_container_block_size(context),
+                ),
+            ),
+        };
+        CSSPixelLength::new((container_length.to_f64_px() * factor as f64 / 100.0) as f32).finite()
+    }
+}
+
+#[cfg(feature = "gecko")]
+fn are_container_queries_enabled() -> bool {
+    static_prefs::pref!("layout.css.container-queries.enabled")
+}
+#[cfg(feature = "servo")]
+fn are_container_queries_enabled() -> bool {
+    false
+}
+
+/// A `<length>` without taking `calc` expressions into account
+///
+/// <https://drafts.csswg.org/css-values/#lengths>
+#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToShmem)]
+pub enum NoCalcLength {
+    /// An absolute length
+    ///
+    /// <https://drafts.csswg.org/css-values/#absolute-length>
+    Absolute(AbsoluteLength),
+
+    /// A font-relative length:
+    ///
+    /// <https://drafts.csswg.org/css-values/#font-relative-lengths>
+    FontRelative(FontRelativeLength),
+
+    /// A viewport-relative length.
+    ///
+    /// <https://drafts.csswg.org/css-values/#viewport-relative-lengths>
+    ViewportPercentage(ViewportPercentageLength),
+
+    /// A container query length.
+    ///
+    /// <https://drafts.csswg.org/css-contain-3/#container-lengths>
+    ContainerRelative(ContainerRelativeLength),
+    /// HTML5 "character width", as defined in HTML5 § 14.5.4.
+    ///
+    /// This cannot be specified by the user directly and is only generated by
+    /// `Stylist::synthesize_rules_for_legacy_attributes()`.
+    ServoCharacterWidth(CharacterWidth),
+}
+
+impl NoCalcLength {
+    /// Return the unitless, raw value.
+    pub fn unitless_value(&self) -> CSSFloat {
+        match *self {
+            Self::Absolute(v) => v.unitless_value(),
+            Self::FontRelative(v) => v.unitless_value(),
+            Self::ViewportPercentage(v) => v.unitless_value(),
+            Self::ContainerRelative(v) => v.unitless_value(),
+            Self::ServoCharacterWidth(c) => c.0 as f32,
+        }
+    }
+
+    // Return the unit, as a string.
+    fn unit(&self) -> &'static str {
+        match *self {
+            Self::Absolute(v) => v.unit(),
+            Self::FontRelative(v) => v.unit(),
+            Self::ViewportPercentage(v) => v.unit(),
+            Self::ContainerRelative(v) => v.unit(),
+            Self::ServoCharacterWidth(_) => "",
+        }
+    }
+
+    /// Returns whether the value of this length without unit is less than zero.
+    pub fn is_negative(&self) -> bool {
+        self.unitless_value().is_sign_negative()
+    }
+
+    /// Returns whether the value of this length without unit is equal to zero.
+    pub fn is_zero(&self) -> bool {
+        self.unitless_value() == 0.0
+    }
+
+    /// Returns whether the value of this length without unit is infinite.
+    pub fn is_infinite(&self) -> bool {
+        self.unitless_value().is_infinite()
+    }
+
+    /// Returns whether the value of this length without unit is NaN.
+    pub fn is_nan(&self) -> bool {
+        self.unitless_value().is_nan()
+    }
+
+    /// Whether text-only zoom should be applied to this length.
+    ///
+    /// Generally, font-dependent/relative units don't get text-only-zoomed,
+    /// because the font they're relative to should be zoomed already.
+    pub fn should_zoom_text(&self) -> bool {
+        match *self {
+            Self::Absolute(..) | Self::ViewportPercentage(..) | Self::ContainerRelative(..) => true,
+            Self::ServoCharacterWidth(..) | Self::FontRelative(..) => false,
+        }
+    }
+
+    /// Parse a given absolute or relative dimension.
+    pub fn parse_dimension(
+        context: &ParserContext,
+        value: CSSFloat,
+        unit: &str,
+    ) -> Result<Self, ()> {
+        Ok(match_ignore_ascii_case! { unit,
+            "px" => Self::Absolute(AbsoluteLength::Px(value)),
+            "in" => Self::Absolute(AbsoluteLength::In(value)),
+            "cm" => Self::Absolute(AbsoluteLength::Cm(value)),
+            "mm" => Self::Absolute(AbsoluteLength::Mm(value)),
+            "q" => Self::Absolute(AbsoluteLength::Q(value)),
+            "pt" => Self::Absolute(AbsoluteLength::Pt(value)),
+            "pc" => Self::Absolute(AbsoluteLength::Pc(value)),
+            // font-relative
+            "em" => Self::FontRelative(FontRelativeLength::Em(value)),
+            "ex" => Self::FontRelative(FontRelativeLength::Ex(value)),
+            "ch" => Self::FontRelative(FontRelativeLength::Ch(value)),
+            "cap" => Self::FontRelative(FontRelativeLength::Cap(value)),
+            "ic" => Self::FontRelative(FontRelativeLength::Ic(value)),
+            "rem" => Self::FontRelative(FontRelativeLength::Rem(value)),
+            // viewport percentages
+            "vw" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Vw(value))
+            },
+            "svw" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Svw(value))
+            },
+            "lvw" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Lvw(value))
+            },
+            "dvw" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Dvw(value))
+            },
+            "vh" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Vh(value))
+            },
+            "svh" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Svh(value))
+            },
+            "lvh" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Lvh(value))
+            },
+            "dvh" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Dvh(value))
+            },
+            "vmin" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Vmin(value))
+            },
+            "svmin" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Svmin(value))
+            },
+            "lvmin" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Lvmin(value))
+            },
+            "dvmin" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Dvmin(value))
+            },
+            "vmax" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Vmax(value))
+            },
+            "svmax" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Svmax(value))
+            },
+            "lvmax" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Lvmax(value))
+            },
+            "dvmax" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Dvmax(value))
+            },
+            "vb" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Vb(value))
+            },
+            "svb" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Svb(value))
+            },
+            "lvb" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Lvb(value))
+            },
+            "dvb" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Dvb(value))
+            },
+            "vi" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Vi(value))
+            },
+            "svi" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Svi(value))
+            },
+            "lvi" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Lvi(value))
+            },
+            "dvi" if !context.in_page_rule() => {
+                Self::ViewportPercentage(ViewportPercentageLength::Dvi(value))
+            },
+            // Container query lengths. Inherit the limitation from viewport units since
+            // we may fall back to them.
+            "cqw" if !context.in_page_rule() && are_container_queries_enabled() => {
+                Self::ContainerRelative(ContainerRelativeLength::Cqw(value))
+            },
+            "cqh" if !context.in_page_rule() && are_container_queries_enabled() => {
+                Self::ContainerRelative(ContainerRelativeLength::Cqh(value))
+            },
+            "cqi" if !context.in_page_rule() && are_container_queries_enabled() => {
+                Self::ContainerRelative(ContainerRelativeLength::Cqi(value))
+            },
+            "cqb" if !context.in_page_rule() && are_container_queries_enabled() => {
+                Self::ContainerRelative(ContainerRelativeLength::Cqb(value))
+            },
+            "cqmin" if !context.in_page_rule() && are_container_queries_enabled() => {
+                Self::ContainerRelative(ContainerRelativeLength::Cqmin(value))
+            },
+            "cqmax" if !context.in_page_rule() && are_container_queries_enabled() => {
+                Self::ContainerRelative(ContainerRelativeLength::Cqmax(value))
+            },
+            _ => return Err(()),
+        })
+    }
+
+    pub(crate) fn try_op<O>(&self, other: &Self, op: O) -> Result<Self, ()>
+    where
+        O: Fn(f32, f32) -> f32,
+    {
+        use self::NoCalcLength::*;
+
+        if std::mem::discriminant(self) != std::mem::discriminant(other) {
+            return Err(());
+        }
+
+        Ok(match (self, other) {
+            (&Absolute(ref one), &Absolute(ref other)) => Absolute(one.try_op(other, op)?),
+            (&FontRelative(ref one), &FontRelative(ref other)) => {
+                FontRelative(one.try_op(other, op)?)
+            },
+            (&ViewportPercentage(ref one), &ViewportPercentage(ref other)) => {
+                ViewportPercentage(one.try_op(other, op)?)
+            },
+            (&ContainerRelative(ref one), &ContainerRelative(ref other)) => {
+                ContainerRelative(one.try_op(other, op)?)
+            },
+            (&ServoCharacterWidth(ref one), &ServoCharacterWidth(ref other)) => {
+                ServoCharacterWidth(CharacterWidth(op(one.0 as f32, other.0 as f32) as i32))
+            },
+            // See https://github.com/rust-lang/rust/issues/68867. rustc isn't
+            // able to figure it own on its own so we help.
+            _ => unsafe {
+                match *self {
+                    Absolute(..) |
+                    FontRelative(..) |
+                    ViewportPercentage(..) |
+                    ContainerRelative(..) |
+                    ServoCharacterWidth(..) => {},
+                }
+                debug_unreachable!("Forgot to handle unit in try_op()")
+            },
+        })
+    }
+
+    pub(crate) fn map(&self, mut op: impl FnMut(f32) -> f32) -> Self {
+        use self::NoCalcLength::*;
+
+        match self {
+            Absolute(ref one) => Absolute(one.map(op)),
+            FontRelative(ref one) => FontRelative(one.map(op)),
+            ViewportPercentage(ref one) => ViewportPercentage(one.map(op)),
+            ContainerRelative(ref one) => ContainerRelative(one.map(op)),
+            ServoCharacterWidth(ref one) => {
+                ServoCharacterWidth(CharacterWidth(op(one.0 as f32) as i32))
+            },
+        }
+    }
+
+    /// Get a px value without context.
+    #[inline]
+    pub fn to_computed_pixel_length_without_context(&self) -> Result<CSSFloat, ()> {
+        match *self {
+            Self::Absolute(len) => Ok(CSSPixelLength::new(len.to_px()).finite().px()),
+            _ => Err(()),
+        }
+    }
+
+    /// Get an absolute length from a px value.
+    #[inline]
+    pub fn from_px(px_value: CSSFloat) -> NoCalcLength {
+        NoCalcLength::Absolute(AbsoluteLength::Px(px_value))
+    }
+}
+
+impl ToCss for NoCalcLength {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
+        crate::values::serialize_specified_dimension(
+            self.unitless_value(),
+            self.unit(),
+            false,
+            dest,
+        )
+    }
+}
+
+impl SpecifiedValueInfo for NoCalcLength {}
+
+impl PartialOrd for NoCalcLength {
+    fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
+        use self::NoCalcLength::*;
+
+        if std::mem::discriminant(self) != std::mem::discriminant(other) {
+            return None;
+        }
+
+        match (self, other) {
+            (&Absolute(ref one), &Absolute(ref other)) => one.to_px().partial_cmp(&other.to_px()),
+            (&FontRelative(ref one), &FontRelative(ref other)) => one.partial_cmp(other),
+            (&ViewportPercentage(ref one), &ViewportPercentage(ref other)) => {
+                one.partial_cmp(other)
+            },
+            (&ContainerRelative(ref one), &ContainerRelative(ref other)) => one.partial_cmp(other),
+            (&ServoCharacterWidth(ref one), &ServoCharacterWidth(ref other)) => {
+                one.0.partial_cmp(&other.0)
+            },
+            // See https://github.com/rust-lang/rust/issues/68867. rustc isn't
+            // able to figure it own on its own so we help.
+            _ => unsafe {
+                match *self {
+                    Absolute(..) |
+                    FontRelative(..) |
+                    ViewportPercentage(..) |
+                    ContainerRelative(..) |
+                    ServoCharacterWidth(..) => {},
+                }
+                debug_unreachable!("Forgot an arm in partial_cmp?")
+            },
+        }
+    }
+}
+
+impl Zero for NoCalcLength {
+    fn zero() -> Self {
+        NoCalcLength::Absolute(AbsoluteLength::Px(0.))
+    }
+
+    fn is_zero(&self) -> bool {
+        NoCalcLength::is_zero(self)
+    }
+}
+
+/// An extension to `NoCalcLength` to parse `calc` expressions.
+/// This is commonly used for the `<length>` values.
+///
+/// <https://drafts.csswg.org/css-values/#lengths>
+#[derive(Clone, Debug, MallocSizeOf, PartialEq, SpecifiedValueInfo, ToCss, ToShmem)]
+pub enum Length {
+    /// The internal length type that cannot parse `calc`
+    NoCalc(NoCalcLength),
+    /// A calc expression.
+    ///
+    /// <https://drafts.csswg.org/css-values/#calc-notation>
+    Calc(Box<CalcLengthPercentage>),
+}
+
+impl From<NoCalcLength> for Length {
+    #[inline]
+    fn from(len: NoCalcLength) -> Self {
+        Length::NoCalc(len)
+    }
+}
+
+impl PartialOrd for FontRelativeLength {
+    fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
+        use self::FontRelativeLength::*;
+
+        if std::mem::discriminant(self) != std::mem::discriminant(other) {
+            return None;
+        }
+
+        match (self, other) {
+            (&Em(ref one), &Em(ref other)) => one.partial_cmp(other),
+            (&Ex(ref one), &Ex(ref other)) => one.partial_cmp(other),
+            (&Ch(ref one), &Ch(ref other)) => one.partial_cmp(other),
+            (&Cap(ref one), &Cap(ref other)) => one.partial_cmp(other),
+            (&Ic(ref one), &Ic(ref other)) => one.partial_cmp(other),
+            (&Rem(ref one), &Rem(ref other)) => one.partial_cmp(other),
+            // See https://github.com/rust-lang/rust/issues/68867. rustc isn't
+            // able to figure it own on its own so we help.
+            _ => unsafe {
+                match *self {
+                    Em(..) | Ex(..) | Ch(..) | Cap(..) | Ic(..) | Rem(..) => {},
+                }
+                debug_unreachable!("Forgot an arm in partial_cmp?")
+            },
+        }
+    }
+}
+
+impl PartialOrd for ContainerRelativeLength {
+    fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
+        use self::ContainerRelativeLength::*;
+
+        if std::mem::discriminant(self) != std::mem::discriminant(other) {
+            return None;
+        }
+
+        match (self, other) {
+            (&Cqw(ref one), &Cqw(ref other)) => one.partial_cmp(other),
+            (&Cqh(ref one), &Cqh(ref other)) => one.partial_cmp(other),
+            (&Cqi(ref one), &Cqi(ref other)) => one.partial_cmp(other),
+            (&Cqb(ref one), &Cqb(ref other)) => one.partial_cmp(other),
+            (&Cqmin(ref one), &Cqmin(ref other)) => one.partial_cmp(other),
+            (&Cqmax(ref one), &Cqmax(ref other)) => one.partial_cmp(other),
+
+            // See https://github.com/rust-lang/rust/issues/68867, then
+            // https://github.com/rust-lang/rust/pull/95161. rustc isn't
+            // able to figure it own on its own so we help.
+            _ => unsafe {
+                match *self {
+                    Cqw(..) | Cqh(..) | Cqi(..) | Cqb(..) | Cqmin(..) | Cqmax(..) => {},
+                }
+                debug_unreachable!("Forgot to handle unit in partial_cmp()")
+            },
+        }
+    }
+}
+
+impl PartialOrd for ViewportPercentageLength {
+    fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
+        use self::ViewportPercentageLength::*;
+
+        if std::mem::discriminant(self) != std::mem::discriminant(other) {
+            return None;
+        }
+
+        match (self, other) {
+            (&Vw(ref one), &Vw(ref other)) => one.partial_cmp(other),
+            (&Svw(ref one), &Svw(ref other)) => one.partial_cmp(other),
+            (&Lvw(ref one), &Lvw(ref other)) => one.partial_cmp(other),
+            (&Dvw(ref one), &Dvw(ref other)) => one.partial_cmp(other),
+            (&Vh(ref one), &Vh(ref other)) => one.partial_cmp(other),
+            (&Svh(ref one), &Svh(ref other)) => one.partial_cmp(other),
+            (&Lvh(ref one), &Lvh(ref other)) => one.partial_cmp(other),
+            (&Dvh(ref one), &Dvh(ref other)) => one.partial_cmp(other),
+            (&Vmin(ref one), &Vmin(ref other)) => one.partial_cmp(other),
+            (&Svmin(ref one), &Svmin(ref other)) => one.partial_cmp(other),
+            (&Lvmin(ref one), &Lvmin(ref other)) => one.partial_cmp(other),
+            (&Dvmin(ref one), &Dvmin(ref other)) => one.partial_cmp(other),
+            (&Vmax(ref one), &Vmax(ref other)) => one.partial_cmp(other),
+            (&Svmax(ref one), &Svmax(ref other)) => one.partial_cmp(other),
+            (&Lvmax(ref one), &Lvmax(ref other)) => one.partial_cmp(other),
+            (&Dvmax(ref one), &Dvmax(ref other)) => one.partial_cmp(other),
+            (&Vb(ref one), &Vb(ref other)) => one.partial_cmp(other),
+            (&Svb(ref one), &Svb(ref other)) => one.partial_cmp(other),
+            (&Lvb(ref one), &Lvb(ref other)) => one.partial_cmp(other),
+            (&Dvb(ref one), &Dvb(ref other)) => one.partial_cmp(other),
+            (&Vi(ref one), &Vi(ref other)) => one.partial_cmp(other),
+            (&Svi(ref one), &Svi(ref other)) => one.partial_cmp(other),
+            (&Lvi(ref one), &Lvi(ref other)) => one.partial_cmp(other),
+            (&Dvi(ref one), &Dvi(ref other)) => one.partial_cmp(other),
+            // See https://github.com/rust-lang/rust/issues/68867. rustc isn't
+            // able to figure it own on its own so we help.
+            _ => unsafe {
+                match *self {
+                    Vw(..) | Svw(..) | Lvw(..) | Dvw(..) | Vh(..) | Svh(..) | Lvh(..) |
+                    Dvh(..) | Vmin(..) | Svmin(..) | Lvmin(..) | Dvmin(..) | Vmax(..) |
+                    Svmax(..) | Lvmax(..) | Dvmax(..) | Vb(..) | Svb(..) | Lvb(..) | Dvb(..) |
+                    Vi(..) | Svi(..) | Lvi(..) | Dvi(..) => {},
+                }
+                debug_unreachable!("Forgot an arm in partial_cmp?")
+            },
+        }
+    }
+}
+
+impl Length {
+    #[inline]
+    fn parse_internal<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+        num_context: AllowedNumericType,
+        allow_quirks: AllowQuirks,
+    ) -> Result<Self, ParseError<'i>> {
+        let location = input.current_source_location();
+        let token = input.next()?;
+        match *token {
+            Token::Dimension {
+                value, ref unit, ..
+            } if num_context.is_ok(context.parsing_mode, value) => {
+                NoCalcLength::parse_dimension(context, value, unit)
+                    .map(Length::NoCalc)
+                    .map_err(|()| location.new_unexpected_token_error(token.clone()))
+            },
+            Token::Number { value, .. } if num_context.is_ok(context.parsing_mode, value) => {
+                if value != 0. &&
+                    !context.parsing_mode.allows_unitless_lengths() &&
+                    !allow_quirks.allowed(context.quirks_mode)
+                {
+                    return Err(location.new_custom_error(StyleParseErrorKind::UnspecifiedError));
+                }
+                Ok(Length::NoCalc(NoCalcLength::Absolute(AbsoluteLength::Px(
+                    value,
+                ))))
+            },
+            Token::Function(ref name) => {
+                let function = CalcNode::math_function(context, name, location)?;
+                let calc = CalcNode::parse_length(context, input, num_context, function)?;
+                Ok(Length::Calc(Box::new(calc)))
+            },
+            ref token => return Err(location.new_unexpected_token_error(token.clone())),
+        }
+    }
+
+    /// Parse a non-negative length
+    #[inline]
+    pub fn parse_non_negative<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        Self::parse_non_negative_quirky(context, input, AllowQuirks::No)
+    }
+
+    /// Parse a non-negative length, allowing quirks.
+    #[inline]
+    pub fn parse_non_negative_quirky<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+        allow_quirks: AllowQuirks,
+    ) -> Result<Self, ParseError<'i>> {
+        Self::parse_internal(
+            context,
+            input,
+            AllowedNumericType::NonNegative,
+            allow_quirks,
+        )
+    }
+
+    /// Get an absolute length from a px value.
+    #[inline]
+    pub fn from_px(px_value: CSSFloat) -> Length {
+        Length::NoCalc(NoCalcLength::from_px(px_value))
+    }
+
+    /// Get a px value without context.
+    pub fn to_computed_pixel_length_without_context(&self) -> Result<CSSFloat, ()> {
+        match *self {
+            Self::NoCalc(ref l) => l.to_computed_pixel_length_without_context(),
+            Self::Calc(ref l) => l.to_computed_pixel_length_without_context(),
+        }
+    }
+}
+
+impl Parse for Length {
+    fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        Self::parse_quirky(context, input, AllowQuirks::No)
+    }
+}
+
+impl Zero for Length {
+    fn zero() -> Self {
+        Length::NoCalc(NoCalcLength::zero())
+    }
+
+    fn is_zero(&self) -> bool {
+        // FIXME(emilio): Seems a bit weird to treat calc() unconditionally as
+        // non-zero here?
+        match *self {
+            Length::NoCalc(ref l) => l.is_zero(),
+            Length::Calc(..) => false,
+        }
+    }
+}
+
+impl Length {
+    /// Parses a length, with quirks.
+    pub fn parse_quirky<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+        allow_quirks: AllowQuirks,
+    ) -> Result<Self, ParseError<'i>> {
+        Self::parse_internal(context, input, AllowedNumericType::All, allow_quirks)
+    }
+}
+
+/// A wrapper of Length, whose value must be >= 0.
+pub type NonNegativeLength = NonNegative<Length>;
+
+impl Parse for NonNegativeLength {
+    #[inline]
+    fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        Ok(NonNegative(Length::parse_non_negative(context, input)?))
+    }
+}
+
+impl From<NoCalcLength> for NonNegativeLength {
+    #[inline]
+    fn from(len: NoCalcLength) -> Self {
+        NonNegative(Length::NoCalc(len))
+    }
+}
+
+impl From<Length> for NonNegativeLength {
+    #[inline]
+    fn from(len: Length) -> Self {
+        NonNegative(len)
+    }
+}
+
+impl NonNegativeLength {
+    /// Get an absolute length from a px value.
+    #[inline]
+    pub fn from_px(px_value: CSSFloat) -> Self {
+        Length::from_px(px_value.max(0.)).into()
+    }
+
+    /// Parses a non-negative length, optionally with quirks.
+    #[inline]
+    pub fn parse_quirky<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+        allow_quirks: AllowQuirks,
+    ) -> Result<Self, ParseError<'i>> {
+        Ok(NonNegative(Length::parse_non_negative_quirky(
+            context,
+            input,
+            allow_quirks,
+        )?))
+    }
+}
+
+/// A `<length-percentage>` value. This can be either a `<length>`, a
+/// `<percentage>`, or a combination of both via `calc()`.
+///
+/// https://drafts.csswg.org/css-values-4/#typedef-length-percentage
+#[allow(missing_docs)]
+#[derive(Clone, Debug, MallocSizeOf, PartialEq, SpecifiedValueInfo, ToCss, ToShmem)]
+pub enum LengthPercentage {
+    Length(NoCalcLength),
+    Percentage(computed::Percentage),
+    Calc(Box<CalcLengthPercentage>),
+}
+
+impl From<Length> for LengthPercentage {
+    fn from(len: Length) -> LengthPercentage {
+        match len {
+            Length::NoCalc(l) => LengthPercentage::Length(l),
+            Length::Calc(l) => LengthPercentage::Calc(l),
+        }
+    }
+}
+
+impl From<NoCalcLength> for LengthPercentage {
+    #[inline]
+    fn from(len: NoCalcLength) -> Self {
+        LengthPercentage::Length(len)
+    }
+}
+
+impl From<Percentage> for LengthPercentage {
+    #[inline]
+    fn from(pc: Percentage) -> Self {
+        if let Some(clamping_mode) = pc.calc_clamping_mode() {
+            LengthPercentage::Calc(Box::new(CalcLengthPercentage {
+                clamping_mode,
+                node: CalcNode::Leaf(calc::Leaf::Percentage(pc.get())),
+            }))
+        } else {
+            LengthPercentage::Percentage(computed::Percentage(pc.get()))
+        }
+    }
+}
+
+impl From<computed::Percentage> for LengthPercentage {
+    #[inline]
+    fn from(pc: computed::Percentage) -> Self {
+        LengthPercentage::Percentage(pc)
+    }
+}
+
+impl Parse for LengthPercentage {
+    #[inline]
+    fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        Self::parse_quirky(context, input, AllowQuirks::No)
+    }
+}
+
+impl LengthPercentage {
+    #[inline]
+    /// Returns a `0%` value.
+    pub fn zero_percent() -> LengthPercentage {
+        LengthPercentage::Percentage(computed::Percentage::zero())
+    }
+
+    #[inline]
+    /// Returns a `100%` value.
+    pub fn hundred_percent() -> LengthPercentage {
+        LengthPercentage::Percentage(computed::Percentage::hundred())
+    }
+
+    fn parse_internal<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+        num_context: AllowedNumericType,
+        allow_quirks: AllowQuirks,
+    ) -> Result<Self, ParseError<'i>> {
+        let location = input.current_source_location();
+        let token = input.next()?;
+        match *token {
+            Token::Dimension {
+                value, ref unit, ..
+            } if num_context.is_ok(context.parsing_mode, value) => {
+                return NoCalcLength::parse_dimension(context, value, unit)
+                    .map(LengthPercentage::Length)
+                    .map_err(|()| location.new_unexpected_token_error(token.clone()));
+            },
+            Token::Percentage { unit_value, .. }
+                if num_context.is_ok(context.parsing_mode, unit_value) =>
+            {
+                return Ok(LengthPercentage::Percentage(computed::Percentage(
+                    unit_value,
+                )));
+            },
+            Token::Number { value, .. } if num_context.is_ok(context.parsing_mode, value) => {
+                if value != 0. &&
+                    !context.parsing_mode.allows_unitless_lengths() &&
+                    !allow_quirks.allowed(context.quirks_mode)
+                {
+                    return Err(location.new_unexpected_token_error(token.clone()));
+                } else {
+                    return Ok(LengthPercentage::Length(NoCalcLength::from_px(value)));
+                }
+            },
+            Token::Function(ref name) => {
+                let function = CalcNode::math_function(context, name, location)?;
+                let calc =
+                    CalcNode::parse_length_or_percentage(context, input, num_context, function)?;
+                Ok(LengthPercentage::Calc(Box::new(calc)))
+            },
+            _ => return Err(location.new_unexpected_token_error(token.clone())),
+        }
+    }
+
+    /// Parses allowing the unitless length quirk.
+    /// <https://quirks.spec.whatwg.org/#the-unitless-length-quirk>
+    #[inline]
+    pub fn parse_quirky<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+        allow_quirks: AllowQuirks,
+    ) -> Result<Self, ParseError<'i>> {
+        Self::parse_internal(context, input, AllowedNumericType::All, allow_quirks)
+    }
+
+    /// Parse a non-negative length.
+    ///
+    /// FIXME(emilio): This should be not public and we should use
+    /// NonNegativeLengthPercentage instead.
+    #[inline]
+    pub fn parse_non_negative<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        Self::parse_non_negative_quirky(context, input, AllowQuirks::No)
+    }
+
+    /// Parse a non-negative length, with quirks.
+    #[inline]
+    pub fn parse_non_negative_quirky<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+        allow_quirks: AllowQuirks,
+    ) -> Result<Self, ParseError<'i>> {
+        Self::parse_internal(
+            context,
+            input,
+            AllowedNumericType::NonNegative,
+            allow_quirks,
+        )
+    }
+}
+
+impl Zero for LengthPercentage {
+    fn zero() -> Self {
+        LengthPercentage::Length(NoCalcLength::zero())
+    }
+
+    fn is_zero(&self) -> bool {
+        match *self {
+            LengthPercentage::Length(l) => l.is_zero(),
+            LengthPercentage::Percentage(p) => p.0 == 0.0,
+            LengthPercentage::Calc(_) => false,
+        }
+    }
+}
+
+impl ZeroNoPercent for LengthPercentage {
+    fn is_zero_no_percent(&self) -> bool {
+        match *self {
+            LengthPercentage::Percentage(_) => false,
+            _ => self.is_zero(),
+        }
+    }
+}
+
+/// A specified type for `<length-percentage> | auto`.
+pub type LengthPercentageOrAuto = generics::LengthPercentageOrAuto<LengthPercentage>;
+
+impl LengthPercentageOrAuto {
+    /// Returns a value representing `0%`.
+    #[inline]
+    pub fn zero_percent() -> Self {
+        generics::LengthPercentageOrAuto::LengthPercentage(LengthPercentage::zero_percent())
+    }
+
+    /// Parses a length or a percentage, allowing the unitless length quirk.
+    /// <https://quirks.spec.whatwg.org/#the-unitless-length-quirk>
+    #[inline]
+    pub fn parse_quirky<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+        allow_quirks: AllowQuirks,
+    ) -> Result<Self, ParseError<'i>> {
+        Self::parse_with(context, input, |context, input| {
+            LengthPercentage::parse_quirky(context, input, allow_quirks)
+        })
+    }
+}
+
+/// A wrapper of LengthPercentageOrAuto, whose value must be >= 0.
+pub type NonNegativeLengthPercentageOrAuto =
+    generics::LengthPercentageOrAuto<NonNegativeLengthPercentage>;
+
+impl NonNegativeLengthPercentageOrAuto {
+    /// Returns a value representing `0%`.
+    #[inline]
+    pub fn zero_percent() -> Self {
+        generics::LengthPercentageOrAuto::LengthPercentage(
+            NonNegativeLengthPercentage::zero_percent(),
+        )
+    }
+
+    /// Parses a non-negative length-percentage, allowing the unitless length
+    /// quirk.
+    #[inline]
+    pub fn parse_quirky<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+        allow_quirks: AllowQuirks,
+    ) -> Result<Self, ParseError<'i>> {
+        Self::parse_with(context, input, |context, input| {
+            NonNegativeLengthPercentage::parse_quirky(context, input, allow_quirks)
+        })
+    }
+}
+
+/// A wrapper of LengthPercentage, whose value must be >= 0.
+pub type NonNegativeLengthPercentage = NonNegative<LengthPercentage>;
+
+/// Either a NonNegativeLengthPercentage or the `normal` keyword.
+pub type NonNegativeLengthPercentageOrNormal =
+    GenericLengthPercentageOrNormal<NonNegativeLengthPercentage>;
+
+impl From<NoCalcLength> for NonNegativeLengthPercentage {
+    #[inline]
+    fn from(len: NoCalcLength) -> Self {
+        NonNegative(LengthPercentage::from(len))
+    }
+}
+
+impl Parse for NonNegativeLengthPercentage {
+    #[inline]
+    fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        Self::parse_quirky(context, input, AllowQuirks::No)
+    }
+}
+
+impl NonNegativeLengthPercentage {
+    #[inline]
+    /// Returns a `0%` value.
+    pub fn zero_percent() -> Self {
+        NonNegative(LengthPercentage::zero_percent())
+    }
+
+    /// Parses a length or a percentage, allowing the unitless length quirk.
+    /// <https://quirks.spec.whatwg.org/#the-unitless-length-quirk>
+    #[inline]
+    pub fn parse_quirky<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+        allow_quirks: AllowQuirks,
+    ) -> Result<Self, ParseError<'i>> {
+        LengthPercentage::parse_non_negative_quirky(context, input, allow_quirks).map(NonNegative)
+    }
+}
+
+/// Either a `<length>` or the `auto` keyword.
+///
+/// Note that we use LengthPercentage just for convenience, since it pretty much
+/// is everything we care about, but we could just add a similar LengthOrAuto
+/// instead if we think getting rid of this weirdness is worth it.
+pub type LengthOrAuto = generics::LengthPercentageOrAuto<Length>;
+
+impl LengthOrAuto {
+    /// Parses a length, allowing the unitless length quirk.
+    /// <https://quirks.spec.whatwg.org/#the-unitless-length-quirk>
+    #[inline]
+    pub fn parse_quirky<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+        allow_quirks: AllowQuirks,
+    ) -> Result<Self, ParseError<'i>> {
+        Self::parse_with(context, input, |context, input| {
+            Length::parse_quirky(context, input, allow_quirks)
+        })
+    }
+}
+
+/// Either a non-negative `<length>` or the `auto` keyword.
+pub type NonNegativeLengthOrAuto = generics::LengthPercentageOrAuto<NonNegativeLength>;
+
+/// Either a `<length>` or a `<number>`.
+pub type LengthOrNumber = GenericLengthOrNumber<Length, Number>;
+
+/// A specified value for `min-width`, `min-height`, `width` or `height` property.
+pub type Size = GenericSize<NonNegativeLengthPercentage>;
+
+impl Parse for Size {
+    fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        Size::parse_quirky(context, input, AllowQuirks::No)
+    }
+}
+
+macro_rules! parse_size_non_length {
+    ($size:ident, $input:expr, $auto_or_none:expr => $auto_or_none_ident:ident) => {{
+        let size = $input.try_parse(|input| {
+            Ok(try_match_ident_ignore_ascii_case! { input,
+                #[cfg(feature = "gecko")]
+                "min-content" | "-moz-min-content" => $size::MinContent,
+                #[cfg(feature = "gecko")]
+                "max-content" | "-moz-max-content" => $size::MaxContent,
+                #[cfg(feature = "gecko")]
+                "fit-content" | "-moz-fit-content" => $size::FitContent,
+                #[cfg(feature = "gecko")]
+                "-moz-available" => $size::MozAvailable,
+                $auto_or_none => $size::$auto_or_none_ident,
+            })
+        });
+        if size.is_ok() {
+            return size;
+        }
+    }};
+}
+
+#[cfg(feature = "gecko")]
+fn is_fit_content_function_enabled() -> bool {
+    static_prefs::pref!("layout.css.fit-content-function.enabled")
+}
+#[cfg(feature = "servo")]
+fn is_fit_content_function_enabled() -> bool {
+    false
+}
+
+macro_rules! parse_fit_content_function {
+    ($size:ident, $input:expr, $context:expr, $allow_quirks:expr) => {
+        if is_fit_content_function_enabled() {
+            if let Ok(length) = $input.try_parse(|input| {
+                input.expect_function_matching("fit-content")?;
+                input.parse_nested_block(|i| {
+                    NonNegativeLengthPercentage::parse_quirky($context, i, $allow_quirks)
+                })
+            }) {
+                return Ok($size::FitContentFunction(length));
+            }
+        }
+    };
+}
+
+impl Size {
+    /// Parses, with quirks.
+    pub fn parse_quirky<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+        allow_quirks: AllowQuirks,
+    ) -> Result<Self, ParseError<'i>> {
+        parse_size_non_length!(Size, input, "auto" => Auto);
+        parse_fit_content_function!(Size, input, context, allow_quirks);
+
+        let length = NonNegativeLengthPercentage::parse_quirky(context, input, allow_quirks)?;
+        Ok(GenericSize::LengthPercentage(length))
+    }
+
+    /// Returns `0%`.
+    #[inline]
+    pub fn zero_percent() -> Self {
+        GenericSize::LengthPercentage(NonNegativeLengthPercentage::zero_percent())
+    }
+}
+
+/// A specified value for `max-width` or `max-height` property.
+pub type MaxSize = GenericMaxSize<NonNegativeLengthPercentage>;
+
+impl Parse for MaxSize {
+    fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        MaxSize::parse_quirky(context, input, AllowQuirks::No)
+    }
+}
+
+impl MaxSize {
+    /// Parses, with quirks.
+    pub fn parse_quirky<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+        allow_quirks: AllowQuirks,
+    ) -> Result<Self, ParseError<'i>> {
+        parse_size_non_length!(MaxSize, input, "none" => None);
+        parse_fit_content_function!(MaxSize, input, context, allow_quirks);
+
+        let length = NonNegativeLengthPercentage::parse_quirky(context, input, allow_quirks)?;
+        Ok(GenericMaxSize::LengthPercentage(length))
+    }
+}
+
+/// A specified non-negative `<length>` | `<number>`.
+pub type NonNegativeLengthOrNumber = GenericLengthOrNumber<NonNegativeLength, NonNegativeNumber>;