CSS预处理语言

#header {
  h1 {
    font-size: 26px;
    font-weight: bold;
  }
  p { font-size: 12px;
    a { text-decoration: none;
      &:hover { border-width: 1px }
    }
  }
}

@color: #4D926F;

#header {
  color: @color;
}
h2 {
  color: @color;
}

$nav-color: #F90;
nav {
  $width: 100px;
  width: $width;
  color: $nav-color;
}

.rounded-corners (@radius: 5px) {
  border-radius: @radius;
  -webkit-border-radius: @radius;
  -moz-border-radius: @radius;
}

#header {
  .rounded-corners;
}
#footer {
  .rounded-corners(10px);
}

@mixin rounded-corners ($radius: 5px) {
  border-radius: $radius;
  -webkit-border-radius: $radius;
  -moz-border-radius: $radius;
}

#header {
  @include rounded-corners;
}
#footer {
  @include rounded-corners(10px);
}

.a{
    &:extend(.b);
    font-size: 12px;
}
.b{
    font-weight: bold;
}

.a{
    @extend .b;
    font-size: 12px;
}
.b{
    font-weight: bold;
}