CSS清除浮动

简要回答

1、额外标签法 clear:both

<ul class="cc">
    <li></li>
    <li></li>
    <div style="clear: both;"></div>
</ul>

2、父元素 overflow:hidden

3、双伪类元素 after和before

    .cc:after {
        content: '';
        height: 0;
        line-height: 0;
        display: block;
        visibility: hidden;
        clear: both;
    }

    .cc:after,
    .cc:before {
        content: "";
        display: block;
        clear: both;
    }