Some Structure About CSS Layout Position,Layer[层次] Box Model Visual Formatting Model BFC[block formatting content],IFC[inline formatting content] Style of Format Text Image Link Form Table CSS Reset Link for some node of some Structure 1.1 Position,Layer: CSS z-index 属性的使用方法和层级树的概念 About something that's causing the problem BFC or other 描述问题: 某个元素包含一个子元素,子元素设置顶部负外边距,父元素随子元素向上偏移