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diff --git a/site/content/docs/5.3/utilities/background.md b/site/content/docs/5.3/utilities/background.md new file mode 100644 index 0000000..c17ed84 --- /dev/null +++ b/site/content/docs/5.3/utilities/background.md @@ -0,0 +1,150 @@ +--- +layout: docs +title: Background +description: Convey meaning through `background-color` and add decoration with gradients. +group: utilities +toc: true +--- + +{{< callout info >}} +{{< partial "callouts/warning-color-assistive-technologies.md" >}} +{{< /callout >}} + +## Background color + +Similar to the contextual text color classes, set the background of an element to any contextual class. Background utilities **do not set `color`**, so in some cases you'll want to use `.text-*` [color utilities]({{< docsref "/utilities/colors" >}}). + +{{< callout info >}} +Background utilities like `.bg-*` that generated from our original `$theme-colors` Sass map don't yet respond to color modes, however, any `.bg-*-subtle` utility will. This will be resolved in v6. +{{< /callout >}} + +{{< example >}} +{{< colors.inline >}} +{{- range (index $.Site.Data "theme-colors") }} +<div class="p-3 mb-2 bg-{{ .name }}{{ if .contrast_color }} text-{{ .contrast_color }}{{ else }} text-white{{ end }}">.bg-{{ .name }}</div> +<div class="p-3 mb-2 bg-{{ .name }}-subtle text-emphasis-{{ .name }}">.bg-{{ .name }}-subtle</div> +{{- end -}} +{{< /colors.inline >}} +<p class="p-3 mb-2 bg-body-secondary">.bg-body-secondary</p> +<p class="p-3 mb-2 bg-body-tertiary">.bg-body-tertiary</p> + +<div class="p-3 mb-2 bg-body text-body">.bg-body</div> +<div class="p-3 mb-2 bg-black text-white">.bg-black</div> +<div class="p-3 mb-2 bg-white text-dark">.bg-white</div> +<div class="p-3 mb-2 bg-transparent text-body">.bg-transparent</div> +{{< /example >}} + +## Background gradient + +By adding a `.bg-gradient` class, a linear gradient is added as background image to the backgrounds. This gradient starts with a semi-transparent white which fades out to the bottom. + +Do you need a gradient in your custom CSS? Just add `background-image: var(--bs-gradient);`. + +{{< markdown >}} +{{< colors.inline >}} +{{- range (index $.Site.Data "theme-colors") }} +<div class="p-3 mb-2 bg-{{ .name }} bg-gradient{{ with .contrast_color }} text-{{ . }}{{ else }} text-white{{ end }}">.bg-{{ .name }}.bg-gradient</div> +{{- end -}} +{{< /colors.inline >}} +<div class="p-3 mb-2 bg-black bg-gradient text-white">.bg-black.bg-gradient</div> +{{< /markdown >}} + +## Opacity + +{{< added-in "5.1.0" >}} + +As of v5.1.0, `background-color` utilities are generated with Sass using CSS variables. This allows for real-time color changes without compilation and dynamic alpha transparency changes. + +### How it works + +Consider our default `.bg-success` utility. + +```css +.bg-success { + --bs-bg-opacity: 1; + background-color: rgba(var(--bs-success-rgb), var(--bs-bg-opacity)) !important; +} +``` + +We use an RGB version of our `--bs-success` (with the value of `25, 135, 84`) CSS variable and attached a second CSS variable, `--bs-bg-opacity`, for the alpha transparency (with a default value `1` thanks to a local CSS variable). That means anytime you use `.bg-success` now, your computed `color` value is `rgba(25, 135, 84, 1)`. The local CSS variable inside each `.bg-*` class avoids inheritance issues so nested instances of the utilities don't automatically have a modified alpha transparency. + +### Example + +To change that opacity, override `--bs-bg-opacity` via custom styles or inline styles. + +{{< example >}} +<div class="bg-success p-2 text-white">This is default success background</div> +<div class="bg-success p-2" style="--bs-bg-opacity: .5;">This is 50% opacity success background</div> +{{< /example >}} + +Or, choose from any of the `.bg-opacity` utilities: + +{{< example >}} +<div class="bg-success p-2 text-white">This is default success background</div> +<div class="bg-success p-2 text-white bg-opacity-75">This is 75% opacity success background</div> +<div class="bg-success p-2 text-dark bg-opacity-50">This is 50% opacity success background</div> +<div class="bg-success p-2 text-dark bg-opacity-25">This is 25% opacity success background</div> +<div class="bg-success p-2 text-dark bg-opacity-10">This is 10% opacity success background</div> +{{< /example >}} + +## CSS + +In addition to the following Sass functionality, consider reading about our included [CSS custom properties]({{< docsref "/customize/css-variables" >}}) (aka CSS variables) for colors and more. + +### Sass variables + +Most `background-color` utilities are generated by our theme colors, reassigned from our generic color palette variables. + +{{< scss-docs name="color-variables" file="scss/_variables.scss" >}} + +{{< scss-docs name="theme-color-variables" file="scss/_variables.scss" >}} + +{{< scss-docs name="variable-gradient" file="scss/_variables.scss" >}} + +Grayscale colors are also available, but only a subset are used to generate any utilities. + +{{< scss-docs name="gray-color-variables" file="scss/_variables.scss" >}} + +Variables for setting `background-color` in `.bg-*-subtle` utilities in light and dark mode: + +{{< scss-docs name="theme-bg-subtle-variables" file="scss/_variables.scss" >}} + +{{< scss-docs name="theme-bg-subtle-dark-variables" file="scss/_variables-dark.scss" >}} + +### Sass maps + +Theme colors are then put into a Sass map so we can loop over them to generate our utilities, component modifiers, and more. + +{{< scss-docs name="theme-colors-map" file="scss/_variables.scss" >}} + +Grayscale colors are also available as a Sass map. **This map is not used to generate any utilities.** + +{{< scss-docs name="gray-colors-map" file="scss/_variables.scss" >}} + +RGB colors are generated from a separate Sass map: + +{{< scss-docs name="theme-colors-rgb" file="scss/_maps.scss" >}} + +Background color opacities build on that with their own map that's consumed by the utilities API: + +{{< scss-docs name="utilities-bg-colors" file="scss/_maps.scss" >}} + +Color mode background colors are also available as a Sass map: + +{{< scss-docs name="theme-bg-subtle-map" file="scss/_maps.scss" >}} + +{{< scss-docs name="theme-bg-subtle-dark-map" file="scss/_maps.scss" >}} + +### Sass mixins + +**No mixins are used to generate our background utilities**, but we do have some additional mixins for other situations where you'd like to create your own gradients. + +{{< scss-docs name="gradient-bg-mixin" file="scss/mixins/_gradients.scss" >}} + +{{< scss-docs name="gradient-mixins" file="scss/mixins/_gradients.scss" >}} + +### Sass utilities API + +Background utilities are declared in our utilities API in `scss/_utilities.scss`. [Learn how to use the utilities API.]({{< docsref "/utilities/api#using-the-api" >}}) + +{{< scss-docs name="utils-bg-color" file="scss/_utilities.scss" >}} |