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LESS 1.2.0

LESS 1.2.0

Now available on and NPM.

This release opens up the powerful branching capabilities of mixin guards and pattern-matching as an alternative to conditional statements.

In trying to stay as close as possible to the declarative nature of CSS, LESS has opted to implement conditional execution via guarded mixins, in the vein of @media query feature specifications:

/* a css media query */
@media screen and (device-height: 600px) {
/* a less mixin definition */
.mixin (@height) when (@screen) and (@height = 600px) {

See 'Language -> Pattern Matching' section on

Here's the canonical example:

@base: #f938ab;

.box-shadow(@style, @c) when (iscolor(@c)) {
  box-shadow:         @style @c;
  -webkit-box-shadow: @style @c;
  -moz-box-shadow:    @style @c;
.box-shadow(@style, @alpha: 50%) when (isnumber(@alpha)) {
  .box-shadow(@style, rgba(0, 0, 0, @alpha));
.box { 
  color: saturate(@base, 5%);
  border-color: lighten(@base, 30%);
  div { .box-shadow(0 0 5px, 30%) }

Other changes include:

  • Type-checking functions (iscolor, ispixel, ...), color mix function (from Sass).

  • Improvements to error reporting.

  • Better @media and @import support when using media features.

  • Support for !important on mixin calls.

  • Lots of bug fixes!

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