function fadeBackground(elementId, startColor, endColor, timeMs) {
    var startTime = new Date().getTime();
 
    function stepFade(elementId, startColor, endColor, startTime, endTime) {
        var now = new Date().getTime();
 
        var step = new Array(3);
 
        var progress = (now - startTime) / (endTime - startTime);
 
        step[0] = Math.round(startColor[0] + ((endColor[0] - startColor[0]) * progress));
        step[1] = Math.round(startColor[1] + ((endColor[1] - startColor[1]) * progress));
        step[2] = Math.round(startColor[2] + ((endColor[2] - startColor[2]) * progress));
 
        document.getElementById(elementId).style.backgroundColor
            = "rgb(" + step[0] + "," + step[1] + "," + step[2] + ")";
 
        if (now <= endTime) {
            setTimeout(function() {
                stepFade(elementId, startColor, endColor, startTime, endTime);
            }, 20);
        }
        else {
            document.getElementById(elementId).style.backgroundColor
                = "rgb(" + endColor[0] + "," + endColor[1] + "," + endColor[2] + ")";
        }
    }
 
    stepFade(elementId, startColor, endColor, startTime, startTime + timeMs);
}