Less

1. example

   @base:#f938ab;
   .box-shadow(@style, @c) when(iscolor(@c)){
       -webkit-box-shadow:@style @c;
       box-shadow:@style @c;
   }
   .box-shadow(@sytle,@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-shaow(0 0 5px 30%)}
   }
   

2. Language features

2.1 Variables

@nice-blue:#979699;
@light-blue:@nice-blue+111;

#header{
    color:@light-blue;
}

2.2 Mixins

.borderd{
    border-top:dotted 1px black;
    border-bottom:solid 2px black;
}

#menu a{
color:#111;
.bordered;
}
.post a{
    color:red;
    .bordered;
}

2.3 Nested Rules

#header{
    color:black;
    .navigation{
        font-size:12px;
    }
    .logo{
        width:300px;
    }
}

.clearfix{
    display:block;
    zoom:1;
    &:after{
        content:"";
        display:block;
        font-size:0;
        height:0;
        clear:both;
        visibility:hidden;
    }
}