dim-on-hover() -webkit-transition opacity 1s ease-out &:hover opacity 2 .button padding 5px dim-on-hover() textarea input color #A7A7A7 &:hover color #000 .dim opacity .2 &:hover &.show opacity 1 box-shadow() -webkit-box-shadow arguments -moz-box-shadow arguments box-shadow arguments html.ie8 &, html.ie7 & foo, html.ie6 & border solid 1px arguments[length(arguments) - 1] body #login box-shadow 1px 1px 3px #eee