全屏响应式背景图像

//HTML

//CSS#bg {  position: fixed;   top: 0;   left: 0;    min-width: 100%;  min-height: 100%;}

要么

img.bg {    min-height: 100%;  min-width: 1024px;    width: 100%;  height: auto;    position: fixed;  top: 0;  left: 0;}@media screen and (max-width: 1024px) {   img.bg {    left: 50%;    margin-left: -512px;     }}

要么

//HTML<img src="images/bg.jpg" id="bg" alt="">//CSS#bg { position: fixed; top: 0; left: 0; }.bgwidth { width: 100%; }.bgheight { height: 100%; }//jQuery$(window).load(function() {        var theWindow        = $(window), $bg   = $("#bg"), aspectRatio      = $bg.width() / $bg.height();        function resizeBg() {     if ( (theWindow.width() / theWindow.height()) < aspectRatio ) {         $bg  .removeClass()  .addClass('bgheight');     } else {         $bg  .removeClass()  .addClass('bgwidth');     }        }        theWindow.resize(resizeBg).trigger("resize");});