jQuery("#preloader").delay(350).fadeOut("slow");
<body> <div id="preloader"></div> <img src="http://apod.nasa.gov/apod/image/9712/orionfull_jcc_big.jpg" /> </body>
#preloader {
position:absolute;
top:0;
left:0;
right:0;
bottom:0;
background-color:#fff; /* change if the mask should have another color then white */
z-index:9999; /* makes sure it stays on top */
}