function cssRGBToHex(RGB){
    if (RGB.substr(0, 1) === '#'){
        return RGB;
    }
    
    var digits = /(.*?)rgb\((\d+), (\d+), (\d+)\)/.exec(RGB);
    
    var R = parseInt(digits[2]);
    var G = parseInt(digits[3]);
    var B = parseInt(digits[4]);
    
    var rgb = B | (G << 8) | (R << 16);
    
    return digits[1] + '#' + rgb.toString(16);
}