為什么margin：0 auto；無法居中？
<!DOCTYPE html>
<html>
<head>
??? <meta charset="UTF-8">
?? ?<title>gundong</title>
??? <style type="text/css">
??? *{padding: 0;margin: 0;}
??? #mar{
?? ??? ?width: 400px;
?? ??? ?height: 300px;
?? ??? ?margin: 0? auto;
??? }
??? </style>
</head>
<body>
<marquee id="mar">hello world!</marquee>
</body>
</html>
2016-02-25
marquee標簽不適用?margin: 0? auto;
#mar{
?? ??? ?position:relative;
?? ??? ?left:50%;
?? ??? ?margin-left:-150px;
? ??? ??? ?width: 400px;
??????? height: 300px;
??????? line-height: 300px;??? }
改成這樣吧