@mixin lib-css($_property, $_value, $_addPrefix: 0) {
    #{$_property}: $_value;
    @if ($_addPrefix == 1) {
        -webkit-#{$_property}: $_value;
        -ms-#{$_property}    : $_value;
        -moz-#{$_property}   : $_value;
        -o-#{$_property}     : $_value;
    }
}

@mixin keyframes($animation-name) {
    @-webkit-keyframes #{$animation-name} {
        @content;
    }
    @-moz-keyframes #{$animation-name} {
        @content;
    }
    @-ms-keyframes #{$animation-name} {
        @content;
    }
    @-o-keyframes #{$animation-name} {
        @content;
    }
    @keyframes #{$animation-name} {
        @content;
    }
}

@mixin opacity($opacity) {
    opacity: $opacity;
    $opacity-ie: $opacity * 100;
    filter: alpha(opacity=$opacity-ie); //IE8
}

@mixin placeholder() {
    ::-webkit-input-placeholder {
        @content;
    }
    :-moz-placeholder { /* Firefox 18- */
        @content;
    }
    ::-moz-placeholder { /* Firefox 19+ */
        @content;
    }
    :-ms-input-placeholder {
        @content;
    }
}
