Skip to content

v1.24.0
Compare
Choose a tag to compare
@devongovett devongovett released this 23 Feb 01:03
· 22 commits to master since this release
v1.24.0
4eaed5c

This release adds support the the light-dark() color function, parses CSS system colors, deduplicates custom properties during minification, merges duplicates @keyframes rules, and fixes some bugs.

light-dark()

The light-dark() function allows you to specify a light mode and dark mode color in a single declaration, without needing to write a separate media query rule. In addition, it uses the color-scheme property to control which theme to use, which allows you to set it programmatically. The color-scheme property also inherits so themes can be nested and the nearest ancestor color scheme applies.

Lightning CSS converts the light-dark() function to use CSS variable fallback when your browser targets don't support it natively. For this to work, you must set the color-scheme property on an ancestor element. The following example shows how you can support both operating system and programmatic overrides for the color scheme.

html {
  color-scheme: light dark;
}

html[data-theme=light] {
  color-scheme: light;
}

html[data-theme=dark] {
  color-scheme: dark;
}

button {
  background: light-dark(#aaa, #444);
}

compiles to:

html {
  --lightningcss-light: initial;
  --lightningcss-dark: ;
  color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
  html {
    --lightningcss-light: ;
    --lightningcss-dark: initial;
  }
}

html[data-theme="light"] {
  --lightningcss-light: initial;
  --lightningcss-dark: ;
  color-scheme: light;
}

html[data-theme="dark"] {
  --lightningcss-light: ;
  --lightningcss-dark: initial;
  color-scheme: dark;
}

button {
  background: var(--lightningcss-light, #aaa) var(--lightningcss-dark, #444);
}

Check it out in the playground.

CSS system colors

CSS system colors are now supported during parsing, meaning they can be safely deduplicated when merging rules.

.a {
  background: Highlight;
}

.a {
  background: ButtonText;
}

compiles to:

.a{background:buttontext}

Custom property deduplication

CSS custom properties are now deduplicated when merging rules. The last property value always wins.

.a {
  --foo: red;
}

.a {
  --foo: green;
}

minifies to:

.a{--foo:green}

@keyframes deduplication

@keyframes rules are also now deduplicated during minification. The last rule of the same name wins.

@keyframes a {
  from { opacity: 0 }
  to { opacity: 1 }
}

@keyframes a {
  from { color: red }
  to { color: blue }
}

compiles to:

@keyframes a{0%{color:red}to{color:#00f}}

Other bug fixes

Assets 2