function spectrum(){ 
    var h = Math.random(); 
    var s = 1; 
    var v = 1; 
    var r, g, b; 
     
    var i = Math.floor(h * 6); 
    var f = h * 6 - i; 
    var p = v * (1 - s); 
    var q = v * (1 - f * s); 
    var t = v * (1 - (1 - f) * s); 
     
    switch(i % 6){ 
        case 0: r = v, g = t, b = p; break; 
        case 1: r = q, g = v, b = p; break; 
        case 2: r = p, g = v, b = t; break; 
        case 3: r = p, g = q, b = v; break; 
        case 4: r = t, g = p, b = v; break; 
        case 5: r = v, g = p, b = q; break; 
    } 
      
    var hue = 'rgb(' + Math.floor(r * 255) + ',' + Math.floor(g * 255) + ',' + Math.floor(b * 255) + ')'; 
    $('#welcome').animate( { backgroundColor: hue }, 1000, function() { spectrum(); }); 
}