1 <!DOCTYPE HTML> 2 <html> 3 <head> 4 <meta charset="utf-8"> 5 <title>半透明（用在遮罩层）</title> 6 <style type="text/css"> 7 *{ margin:0; padding:0;} 8 9 #maskLayer{ width:30%; height:200px; background-color:#000000; opacity:0.5; -moz-opacity:0.5; filter:alpha(opacity=50);} 10 11 #div1{ width:100px; height:100px; background:red; } 12 </style> 13 14 </head> 15 <body> 16 17 <div id="maskLayer"> 18 <div id="div1">div1</div> 19 </div> 20 21 </body> 22 </html>