public static function add_prefixes( $css ) {
		if ( is_array( $css ) ) {
			foreach ( $css as $media_query => $elements ) {
				foreach ( $elements as $element => $style_array ) {
					foreach ( $style_array as $property => $value ) {

						// Add -webkit-* and -moz-*.
						if ( is_string( $property ) && in_array(
							$property,
							[
								'border-radius',
								'box-shadow',
								'box-sizing',
								'text-shadow',
								'transform',
								'background-size',
								'transition',
								'transition-property',
							],
							true
						) ) {
							unset( $css[ $media_query ][ $element ][ $property ] );
							$css[ $media_query ][ $element ][ '-webkit-' . $property ] = $value;
							$css[ $media_query ][ $element ][ '-moz-' . $property ]    = $value;
							$css[ $media_query ][ $element ][ $property ]              = $value;
						}

						// Add -ms-* and -o-*.
						if ( is_string( $property ) && in_array(
							$property,
							[
								'transform',
								'background-size',
								'transition',
								'transition-property',
							],
							true
						) ) {
							unset( $css[ $media_query ][ $element ][ $property ] );
							$css[ $media_query ][ $element ][ '-ms-' . $property ] = $value;
							$css[ $media_query ][ $element ][ '-o-' . $property ]  = $value;
							$css[ $media_query ][ $element ][ $property ]          = $value;
						}
					}
				}
			}
		}
		return $css;
	}