var seconds = new Date().getTime() / 1000;

<input type="text" value="3" class="field left" readonly>

.content {
    width: 100%;
    box-sizing: border-box;
}

hr {
 display: block;
 height: 1px;
 border: 0;
 border-top: 1px solid #ccc;
 margin: 1em 0;
 padding: 0; 
}

#demo
{
  background:url(bg_apple_little.gif) no-repeat center center;
  height:200px;
  width:200px;
}

 
function css(a) {
    var sheets = document.styleSheets, o = {};
    for (var i in sheets) {
        var rules = sheets[i].rules || sheets[i].cssRules;
        for (var r in rules) {
            if (a.is(rules[r].selectorText)) {
                o = $.extend(o, css2json(rules[r].style), css2json(a.attr('style')));
            }
        }

tr:nth-child(even) { background-color: #000000; }

以上方法不适用于IE8及以下版本。

也可用通过jQuery的方法实现：

$(document).ready(function() {

  $("tr:even").css("background-color", "#000000");

});

简单的tooltip：

<div title="This is my tooltip">

复杂的tooltip参考：http://www.designer-daily.com/jquery-prototype-mootool-tooltips-12632

 
function css(a) {
    var sheets = document.styleSheets, o = {};
    for (var i in sheets) {
        var rules = sheets[i].rules || sheets[i].cssRules;
        for (var r in rules) {
            if (a.is(rules[r].selectorText)) {
                o = $.extend(o, css2json(rules[r].style), css2json(a.attr('style')));
            }
        }