*{ margin:0; padding:0;}
.right_box{position:fixed;right:0; top:45%; background:#0CF; width:100px; height:200px; cursor:pointer;}
.mask_box{ width:500px; height:300px; border:1px solid #333; box-shadow:0 0 10px #ccc; position:fixed; left:50%; margin-left:-250px; top:50%; margin-top:-150px;display:none}
.mask_box span{ position:absolute; top:0; right:0; width:50px; height:50px; text-align:center; line-height:50px; cursor:pointer; display:block; font-size:24px;}