clearfix mixin of less supports IE6/7
// Refer:
// - http://nicolasgallagher.com/micro-clearfix-hack/
// - http://nicolasgallagher.com/better-float-containment-in-ie/
// - http://www.yuiblog.com/blog/2010/09/27/clearfix-reloaded-overflowhidden-demystified/
.clearfix() {
&:before,
&:after {
content: " "; // 1
display: table; // 2
}
&:after {
clear: both;
}
*zoom: 1;
}