不是學習Python的第一天，跟隨教程做了如下網頁，問題來了，爲啥中央3個圖片不是居中的，右側有多餘空白。
代碼如下
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Hello World!</title>
<link rel="stylesheet" type="text/css" href="main.css">
</head>
<body>
<div class="header">
<img src="images/blah.png">
<ul class="nav">
<li><a href="#">Home</a></li>
<li><a href="#">Site</a></li>
<li><a href="#">Others</a></li>
</ul>
</div>
<div class="main-content">
<h2>The Beach</h2>
<hr>
<div class="photos">
<img src="images/0001.jpg" width="150">
<img src="images/0002.jpg" width="150">
<img src="images/0003.jpg" width="150">
</div>
<p>
Three competing store owners rented adjoining shops in a mall. Observers waited for mayhem to ensue. The retailer on the right put up huge signs saying, "Gigantic Sale!" and "Super Bargains!"
The store on the left raised bigger signs proclaiming, "Prices Slashed!" and "Fantastic Discounts!" The owner in the middle then prepared a large sign that simply stated, "ENTRANCE".
</p>
</div>
<div class="footer">
<p>©lifecoding</p>
</div>
</body>
</html>