function doClear(theText) 
{
     if (theText.value == theText.defaultValue)
 {
         theText.value = ""
     }
 }
 
/**********************************************************************/
/* Resim Hover Opacity için gerekli fonksiyon */
/**********************************************************************/
 
<!--
var itv = 50;
var step = 10;
var start = 0;
var end = 0;
var currentOpac;

//change the opacity for different browsers
function changeOpac(obj, opacity) {
	var object = obj.style; 
	object.opacity = (opacity / 100);
	object.MozOpacity = (opacity / 100);
	object.KhtmlOpacity = (opacity / 100);
	object.filter = "alpha(opacity=" + opacity + ")";
}

function BeginOpacity(obj, s, e)
{
	start = s;
	end = e;
	currentOpac = s;
	theobject=obj;
	changing=setInterval("opacityit(theobject)",itv);
}

function EndOpacity(obj, end){
	clearInterval(changing);
	changeOpac(obj, end);
}

function opacityit(obj){
	if(start > end) {
		if (currentOpac>end){
			currentOpac = currentOpac - step;
			changeOpac(obj,currentOpac);
		}
		else if (window.highlighting)
			clearInterval(highlighting);
	} else if(start < end) {
		if (currentOpac<end){
			currentOpac = currentOpac + step;
			changeOpac(obj,currentOpac);
		}
		else if (window.changing)
			clearInterval(changing);
	}
}
//-->
 

/**********************************************************************/
/* Açılışta çalıştırılacak fonksiyon */
/**********************************************************************/

function anaKatmaniOrtala() {
	var katman = document.getElementById("ana");
	var katmanEn = parseInt("katman.clientWidth");
	var katmanBoy = parseInt("katman.clientHeight");
	var govdeEn = parseInt("document.body.clientWidth");
	var govdeBoy = parseInt("document.body.clientHeight");
	var sol = parseInt((govdeEn/2)-(katmanEn/2))
	var ust = parseInt((govdeBoy/2)-(katmanBoy/2))

	var altKatman = document.getElementById("alt");
	
	if(sol>=0) {
		katman.style.left = sol+"px";
	} else {
		katman.style.left = "0px";
	}

	if(ust>=0) {
		katman.style.top = ust+"px";
	} else {
		katman.style.top = "0px";
	}
	
	var altKatmanUst = parseInt(katman.style.top)+katman.offsetHeight;
	var altKatmanSol = katman.style.left;

	altKatman.style.top = altKatmanUst;
	altKatman.style.left = altKatmanSol;
}

if(window.addEventListener) {
	window.addEventListener("onresize", anaKatmaniOrtala, false);
	window.addEventListener("load", anaKatmaniOrtala, false);
	window.addEventListener("scroll", anaKatmaniOrtala, false);
} else {
	window.attachEvent("onresize", anaKatmaniOrtala);
	window.attachEvent("onload", anaKatmaniOrtala);
	window.attachEvent("onscroll", anaKatmaniOrtala);
}

/**********************************************************************/
/* Sayfa stillerini değiştiren fonksiyon */
/**********************************************************************/

function stilDegistir(stil) {
	var stilElemani = document.getElementById("stil");
	switch(stil) {
		case "gri": stilElemani.href = "inc/css/stiller/gri.css";
		break;

		case "mavi": stilElemani.href = "inc/css/stiller/mavi.css";
		break;

		case "yesil": stilElemani.href = "inc/css/stiller/yesil.css";
		break;

		case "turuncu": stilElemani.href = "inc/css/stiller/turuncu.css";
		break;

		case "kirmizi": stilElemani.href = "inc/css/stiller/kirmizi.css";
		break;

		default: stilElemani.href = "inc/css/stiller/gri.css";
		break;
	}
}

/**********************************************************************/