永远居中的背景图片[修改图片名称]

<script> document.onmouseover = doOver; document.onmouseout = doOut; document.onmousedown = doDown; document.onmouseup = doUp; function doOver() { var toEl = getReal(window.event.toElement, "className", "coolButton"); var fromEl = getReal(window.event.fromElement, "className", "coolButton"); if (toEl == fromEl) return; var el = toEl; var cDisabled = el.cDisabled; cDisabled = (cDisabled != null); // If CDISABLED atribute is present if (el.className == "coolButton") el.onselectstart = new Function("return false"); if ((el.className == "coolButton") && !cDisabled) { makeRaised(el); makeGray(el,false); } } function doOut() { var toEl = getReal(window.event.toElement, "className", "coolButton"); var fromEl = getReal(window.event.fromElement, "className", "coolButton"); if (toEl == fromEl) return; var el = fromEl; var cDisabled = el.cDisabled; cDisabled = (cDisabled != null); // If CDISABLED atribute is present var cToggle = el.cToggle; toggle_disabled = (cToggle != null); // If CTOGGLE atribute is present if (cToggle && el.value) { makePressed(el); makeGray(el,true); } else if ((el.className == "coolButton") && !cDisabled) { makeFlat(el); makeGray(el,true); } } function doDown() { el = getReal(window.event.srcElement, "className", "coolButton"); var cDisabled = el.cDisabled; cDisabled = (cDisabled != null); // If CDISABLED atribute is present if ((el.className == "coolButton") && !cDisabled) { makePressed(el) } } function doUp() { el = getReal(window.event.srcElement, "className", "coolButton"); var cDisabled = el.cDisabled; cDisabled = (cDisabled != null); // If CDISABLED atribute is present if ((el.className == "coolButton") && !cDisabled) { makeRaised(el); } } function getReal(el, type, value) { temp = el; while ((temp != null) && (temp.tagName != "BODY")) { if (eval("temp." + type) == value) { el = temp; return el; } temp = temp.parentElement; } return el; } function findChildren(el, type, value) { var children = el.children; var tmp = new Array(); var j=0; for (var i=0; i<children.length; i++) { if (eval("children[i]." + type + "==\"" + value + "\"")) { tmp[tmp.length] = children[i]; } tmp = tmp.concat(findChildren(children[i], type, value)); } return tmp; } function disable(el) { if (document.readyState != "complete") { window.setTimeout("disable(" + el.id + ")", 100); // If document not finished rendered try later. return; } var cDisabled = el.cDisabled; cDisabled = (cDisabled != null); // If CDISABLED atribute is present if (!cDisabled) { el.cDisabled = true; el.innerHTML = '<span style="background: buttonshadow; width: 100%; height: 100%; text-align: center;">' + '<span style="filter:Mask(Color=buttonface) DropShadow(Color=buttonhighlight, OffX=1, OffY=1, Positive=0); height: 100%; width: 100%%; text-align: center;">' + el.innerHTML + '</span>' + '</span>'; if (el.onclick != null) { el.cDisabled_onclick = el.onclick; el.onclick = null; } } } function enable(el) { var cDisabled = el.cDisabled; cDisabled = (cDisabled != null); // If CDISABLED atribute is present if (cDisabled) { el.cDisabled = null; el.innerHTML = el.children[0].children[0].innerHTML; if (el.cDisabled_onclick != null) { el.onclick = el.cDisabled_onclick; el.cDisabled_onclick = null; } } } function addToggle(el) { var cDisabled = el.cDisabled; cDisabled = (cDisabled != null); // If CDISABLED atribute is present var cToggle = el.cToggle; cToggle = (cToggle != null); // If CTOGGLE atribute is present if (!cToggle && !cDisabled) { el.cToggle = true; if (el.value == null) el.value = 0; // Start as not pressed down if (el.onclick != null) el.cToggle_onclick = el.onclick; // Backup the onclick else el.cToggle_onclick = ""; el.onclick = new Function("toggle(" + el.id +"); " + el.id + ".cToggle_onclick();"); } } function removeToggle(el) { var cDisabled = el.cDisabled; cDisabled = (cDisabled != null); // If CDISABLED atribute is present var cToggle = el.cToggle; cToggle = (cToggle != null); // If CTOGGLE atribute is present if (cToggle && !cDisabled) { el.cToggle = null; if (el.value) { toggle(el); } makeFlat(el); if (el.cToggle_onclick != null) { el.onclick = el.cToggle_onclick; el.cToggle_onclick = null; } } } function toggle(el) { el.value = !el.value; if (el.value) el.style.background = "URL(/images/tileback.gif)"; else el.style.backgroundImage = ""; // doOut(el); } function makeFlat(el) { with (el.style) { background = ""; border = "1px solid buttonface"; padding = "1px"; } } function makeRaised(el) { with (el.style) { borderLeft = "1px solid buttonhighlight"; borderRight = "1px solid buttonshadow"; borderTop = "1px solid buttonhighlight"; borderBottom = "1px solid buttonshadow"; padding = "1px"; } } function makePressed(el) { with (el.style) { borderLeft = "1px solid buttonshadow"; borderRight = "1px solid buttonhighlight"; borderTop = "1px solid buttonshadow"; borderBottom = "1px solid buttonhighlight"; paddingTop = "2px"; paddingLeft = "2px"; paddingBottom = "0px"; paddingRight = "0px"; } } function makeGray(el,b) { var filtval; if (b) filtval = "gray()"; else filtval = ""; var imgs = findChildren(el, "tagName", "IMG"); for (var i=0; i<imgs.length; i++) { imgs[i].style.filter = filtval; } } document.write("<style>"); document.write(".coolBar {background: buttonface;border-top: 1px solid buttonhighlight; border-left: 1px solid buttonhighlight; border-bottom: 1px solid buttonshadow; border-right: 1px solid buttonshadow; padding: 2px; font: menu;}"); document.write(".coolButton {border: 1px solid buttonface; padding: 1px; text-align: center; cursor: default;}"); document.write(".coolButton IMG {filter: gray();}"); document.write("</style>"); </script>  <table class="coolBar"> <tr> <td class="coolButton"> <font size="3"><b><font color="#000000">Home</font></b></font> </td> <td class="coolButton"> <font size="3"><b><font color="#000000">Link</font></b></font> </td> </tr> </table>