@mixin border-radius($radius) {
    -webkit-border-radius:$radius;
       -moz-border-radius:$radius;
        -ms-border-radius:$radius;
         -o-border-radius:$radius;
            border-radius:$radius;
}
@mixin left-border-radius($radius){
    -webkit-border-radius:$radius 0 0 $radius;
       -moz-border-radius:$radius 0 0 $radius;
        -ms-border-radius:$radius 0 0 $radius;
         -o-border-radius:$radius 0 0 $radius;
            border-radius:$radius 0 0 $radius;
}
@mixin top-border-radius($radius){
    -webkit-border-radius:$radius $radius 0 0;
       -moz-border-radius:$radius $radius 0 0;
        -ms-border-radius:$radius $radius 0 0;
         -o-border-radius:$radius $radius 0 0;
            border-radius:$radius $radius 0 0;
}

@mixin linear-transition($action){
    -webkit-transition:$action;
       -moz-transition:$action;
        -ms-transition:$action;
         -o-transition:$action;
            transition:$action;
}
@mixin background_rgba($r, $g, $b, $opacity){
    background:rgba($r, $g, $b, $opacity);
}
@mixin transform-rotate($deg){
    -webkit-transform:rotate($deg);
        -ms-transform:rotate($deg);
            transform:rotate($deg);
}