1 files changed, 85 insertions, 0 deletions
diff --git a/toolkit/themes/linux/global/popup.css b/toolkit/themes/linux/global/popup.css
new file mode 100644
index 0000000000..acd11c9359
--- /dev/null
+++ b/toolkit/themes/linux/global/popup.css
@@ -0,0 +1,85 @@
+/* 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 http://mozilla.org/MPL/2.0/. */
+
+@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
+@namespace html url("http://www.w3.org/1999/xhtml");
+
+/* ::::: menupopup ::::: */
+
+menupopup,
+panel {
+  min-width: 1px;
+  --panel-padding-block: max(0px, var(--panel-border-radius) / 2 - 1px);
+  --panel-padding: var(--panel-padding-block) 0;
+  --panel-color: MenuText;
+  --panel-background: Menu;
+  --panel-border-radius: 8px;
+  --panel-border-color: ThreeDShadow;
+  --panel-width: initial;
+  --panel-shadow: 0 0 var(--panel-shadow-margin) hsla(0,0%,0%,.2);
+  /* To account for the box-shadow below */
+  --panel-shadow-margin: 4px;
+  margin: calc(-1 * var(--panel-shadow-margin));
+  -moz-window-input-region-margin: var(--panel-shadow-margin);
+}
+
+menupopup {
+  /* Also apply the padding in the inline axis for menus */
+  --panel-padding: var(--panel-padding-block);
+}
+
+@media (prefers-contrast) {
+  menupopup,
+  panel {
+    --panel-border-color: color-mix(in srgb, currentColor 60%, transparent);
+  }
+}
+
+menupopup > menu > menupopup {
+  /* Vertically align nested menupopups: the shadow plus the top padding */
+  margin-top: calc(-1 * (var(--panel-shadow-margin) + var(--panel-padding-block)));
+}
+
+/* ::::: arrow panel ::::: */
+
+:is(panel, menupopup)[type="arrow"] {
+  border: none;
+  background-color: transparent;
+}
+
+:is(panel, menupopup)::part(content) {
+  display: flex;
+  box-sizing: border-box;
+  padding: var(--panel-padding);
+  color: var(--panel-color);
+  background: var(--panel-background);
+  border-radius: var(--panel-border-radius);
+  border: 1px solid var(--panel-border-color);
+  width: var(--panel-width);
+  min-width: 0;
+  min-height: 0;
+
+  /* Makes popup constraints work */
+  max-height: calc(100% - 2 * var(--panel-shadow-margin));
+  max-width: calc(100% - 2 * var(--panel-shadow-margin));
+
+  box-shadow: var(--panel-shadow);
+  margin: var(--panel-shadow-margin);
+}
+
+:is(panel, menupopup)[orient=vertical]::part(content) {
+  flex-direction: column;
+}
+
+panel[type="arrow"].panel-no-padding::part(content) {
+  padding: 0;
+  overflow: hidden; /* Don't let panel content overflow the border */
+}
+
+/* rules for popups associated with menulists */
+
+menulist > menupopup {
+  padding: 0;
+  min-width: 0;
+}