主要疑惑是main、left、right三个元素放置顺序的问题
先贴代码：
Lorem ipsum dolor sit amet, consectetur adipisicing elit. Architecto, ut!
Lorem ipsum dolor sit amet, consectetur adipisicing elit. Similique accusamus rem laudantium nam, temporibus sit cumque, asperiores eveniet praesentium omnis vero saepe dicta. Possimus facere ipsum, voluptas aliquid illo veniam?
Lorem ipsum dolor sit amet, consectetur adipisicing elit. Maxime ea hic quaerat neque reprehenderit doloremque minima architecto, ipsa sed temporibus recusandae vitae impedit cum pariatur aspernatur similique dolorem libero a minus eveniet dolor sapiente! Illo minus dicta est! Accusantium, assumenda amet unde beatae cumque molestias. Numquam aut laudantium fugit, similique tempora minima vitae veniam obcaecati dolor, nihil rerum enim! Accusamus soluta facilis nihil, maiores eos esse quo dignissimos, nisi illo molestias aliquam, beatae quibusdam. Similique nesciunt velit eius aut aperiam est temporibus voluptatem ullam omnis, recusandae rerum vel incidunt nihil, voluptatum excepturi, accusamus ducimus totam quasi? Minima maxime tempore labore.
body{ margin: 0; overflow: hidden; } .out{ overflow: hidden; width: 100%; height: 100%; } .main{ margin: 0 210px; background-color: lightgreen; } .left{ width: 200px; float: left; background-color: pink; } .right{ width: 200px; float: right; background-color: pink; } .main,.left,.right{ margin-bottom: -9999px; padding-bottom: 9999px; }按照left、right、main的顺序
按照left、main、right的顺序
按照main、left、right的顺序
无法理解为什么会存在这样三种情况。。。
http://www.cnblogs.com/xiaohuochai/p/5314289.html?plg_nld=1&plg_uin=1&plg_auth=1&plg_nld=1&plg_usr=1&plg_vkey=1&plg_dev=1
原贴中三列等高布局的CSS写法，main本来就不浮动的，关键在于margin-bottom 和padding-bottom负补偿。
回答问题前看清楚问题行不 :(
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First of all, understand that float will turn the element into an inline-block and display it in a row
So:
In the order of left, right, main:
left, right become a row, Then main is added, just into one line
and in the order of left, main, right:
left, when main, because main is a p, the block element occupies its own line, so it breaks the line.
In the order of main, left, right:
Same as above
Actually, this is just some principles of floating and has nothing to do with negative margin compensation. I suggest the poster to study the principle of floating. I can't explain it clearly in one or two sentences.