SCSS (SASS) Input Placeholder Template

style.scss

@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;
    }
}

.foobar {
    @include placeholder {
        color: #AAAAAA;
    }
}