@mixin display($value) {
	-webkit-display: $value;
	-khtml-display: $value;
	-moz-display: $value;
	-ms-display: $value;
	-o-display: $value;
	display: $value;
}

@mixin appearance($value) {
	-webkit-appearance: $value;
	-moz-appearance: $value;
	-ms-appearance: $value;
	-o-appearance: $value;
	appearance: $value;
}

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

@mixin backface-visibility($visibility) {
    -webkit-backface-visibility: $visibility;
    -moz-backface-visibility: $visibility;
    -ms-backface-visibility: $visibility;
    -o-backface-visibility: $visibility;
    backface-visibility: $visibility;
}

@mixin placeholder {
    &::-webkit-input-placeholder {
		@content;
	}
    &:-moz-placeholder {
		@content;
	}
    &::-moz-placeholder {
		@content;
	}
    &:-ms-input-placeholder {
        @content;
    }
}