1、概念,全稱是block format context,塊級格式化上下文
2、觸發條件
根元素 float屬性不為none
position為absolute或fixed
display為inline-block, table-cell, table-caption, flex, inline-flex
overflow不為visible
3、應用場景
自適應兩欄布局
<style> body { width: 300px; position: relative; } .aside { width: 100px; height: 150px; float: left; background: #f66; } .main { height: 200px; background: #fcc; } </style> <body> <div class="aside"></div> <div class="main"></div> </body>
清除浮動
<style> .par { border: 5px solid #fcc; width: 300px; overflow:hidden; } .child { border: 5px solid #f66; width:100px; height: 100px; float: left; } </style> <body> <div class="par"> <div class="child"></div> <div class="child"></div> </div> </body>
防止垂直 margin 重疊
<style> p { color: #f55; background: #fcc; width: 200px; line-height: 100px; text-align:center; margin: 100px; } </style> <body> <p>Haha</p> <p>Hehe</p> </body>