學習 overflow:hidden,scroll,auto,visible
overflow-x和overflow-y
overflow-x，overflow-y和overflow的用法是一樣的，只是特地的指定了x與y軸而已。我這裏只寫了overflow的用法。
1.不添加overflow樣式
首先上代碼：限定了div的寬度和高度，但是裏面的內容缺超出了div的大小。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>盒子中顯示不下的內容的學習</title>
<style>
div{
width: 400px;
height: 400px;
background-color: aqua;
}
</style>
</head>
<body>
<div>
<h1>默認</h1>
<p>
hellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohello
hellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohello
hellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohello
hellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohello
hellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohello
hellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohello</p>
<p>
hellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohello
hellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohello
hellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohello
hellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohello
hellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohello
hellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohello</p>
</div>
</body>
</html>得到的效果如是這樣的：
