@function double($var){
	@return $var * 2;
}

@function half($var){
	@return $var / 2;
}

@mixin absolute-element() {
    display: block;
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    z-index: 1;
}

@mixin transition($ms: $transition-time) {
	transition: all $ms $transition-method;
}

@mixin optional-at-root($sel) {
    @at-root #{if(not &, $sel, selector-append(&, $sel))} {
        @content;
    }
}

@mixin placeholder {
    @include optional-at-root('::-webkit-input-placeholder') {
        @content;
    }
    @include optional-at-root(':-moz-placeholder') {
        @content;
    }
    @include optional-at-root('::-moz-placeholder') {
      @content;
    }
    @include optional-at-root(':-ms-input-placeholder') {
       @content;
    }
}