CSS-note

 margin: 2em  0      2em   0;
 /*      top  right  bottom left;  */

 margin:    2em          0;
 /*     top&bottom   left&right   */

 margin: 2em      0       2em;
 /*       top  right&left  bottom  */

我要怎樣在滑鼠游標移動到表格中某列時，改變背景色。
for Mozilla

.datatable tr:hover{
     background-color: #DFE7F2;
     cololr: #000000;
}

for IE (:hover在Internet Explorer上，仍無法作用於連結之外的元素)

.datatable tr:hover, .datatable tr.hilite{
     background-color: #DFE7F2;
     color: #000000;
}

<script type="text/javascript">
var rows = document.getElementByTagName("tr");
for(var i=0; i<rows.length; i++){
     rows[i].onmouseover = function(){
          this.className += ' hilite';
     }
     rows[i].onmouseout = function(){
          this.className = this.className.repalce('hilite', ' ');
     }
}
</scrit>

!important Declaration
The following example includes the !important declaration in the style rule. Normally the color of the text would be green, because inline styles override the rules set in a style tag. By including the !important declaration in the style rule, you set the content of the paragraph to red.

<STYLE>
     P { color:red!important }
</STYLE>
<P STYLE="color:green">This text will be red.</P>