Javascript 改变css类，直接操作css，非遍历所有dom法

<div id="test_chg">
Look At Me,<a href="javascript:gogo();void(0)">Change me</a>!<br />
<span id="curcss"></span>
</div>
<script language="javascript">
var g={
    E:function (c) {
if (typeof c === "string") {
return document.getElementById(c);
        } else {
return c;
        }
    },    
    C:function (c) {
var d;
        c = c.toUpperCase();
if (c == "TEXT") {
            d = document.createTextNode("");
        } else {
if (c == "BUFFER") {
                d = document.createDocumentFragment();
            } else {
                d = document.createElement(c);
            }
        }
return d;
    }
}
function gogo()
{
var y = g.E("custom_style");
if (!g.E("custom_style")) {
        y = g.C("style");
        y.setAttribute("type", "text/css");
        y.id = "custom_style"
    }
    W=[];
    W.push('#test_chg{color:'+'rgb('+rand(1,255)+','+rand(1,255)+','+rand(1,255)+');');
    W.push('font-size:'+rand(21,32)+'px}');
    document.getElementsByTagName("head")[0].appendChild(y);
var N=W.join('\n');
if (y.styleSheet) {
        y.styleSheet.cssText = N
    } else {
        y.innerHTML = N
    }
    g.E('curcss').innerHTML=N
}
</script>