protected static function readCss( $path, $class_prefix = 'fa-' ) {
		//if path is incorrect or file does not exist, stop.
		if ( ! file_exists( $path ) ) {
			throw new \Exception( 'Can\'t read the CSS. File does not exists.' );
		}

		$css     = file_get_contents( $path );
		$pattern = '/\.(' . $class_prefix . '(?:\w+(?:-)?)+):before\s+{\s*content:\s*"(.+)";\s+}/';

		preg_match_all( $pattern, $css, $matches, PREG_SET_ORDER );

		$icons = array();
		foreach ( $matches as $match ) {
			$icons[ $match[1] ] = $match[2];
		}

		return $icons;
	}