在CSS规范中它定义了这种行为？
正如这两篇文章所述......
当您浮动元素时,它将变为块框
浮动的元素是自动的
display: block;
示例: https ://jsfiddle.net/kennethcss/y6cmgubt/
a {
/* for looks */
background-color: #e1e1e1;
line-height: 30px;
text-align: center;
/* Comment "float: left" out to test. Once the float is removed, neither
* the height or width have any effect on the anchor because its default
* display is inline.
*/
height: 30px;
float: left;
width: 100px;
}<nav>
<a>Nav Item 1</a>
<a>Nav Item 2</a>
<a>Nav Item 3</a>
</nav>