Untitled

<html>
<head>
<script>
function shadeColor(color, shade) {
    var colorInt = parseInt(color.substring(1),16);

    var R = (colorInt & 0xFF0000) >> 16;
    var G = (colorInt & 0x00FF00) >> 8;
    var B = (colorInt & 0x0000FF) >> 0;

    R = R + Math.floor((shade/255)*R);
    G = G + Math.floor((shade/255)*G);
    B = B + Math.floor((shade/255)*B);

    var newColorInt = (R<<16) + (G<<8) + (B);
    var newColorStr = "#"+newColorInt.toString(16);

    return newColorStr;
}

function printButtonClick() {
    var textbox = document.getElementById("dynatext");
    var color = textbox.value;
    textbox.value = shadeColor(color, -10);
    textbox.style.background=color;
}
</script>
</head>
<body>
    <input type="text" id="dynatext">
    <input type="button" value="Print" onclick="printButtonClick();"/>
</body>
</html>