Html编码规范

• 子元素比父元素缩进两个字符

<div class="layer2">
      <div class="layer2-1"><h2>盒子2-1</h2></div>
      <div class="layer2-2"><h2>盒子2-2</h2></div>
 </div>  

• 选择符命名要层次清楚，含义分明，如可以命名为section、layer2、layer2-2等。

<div id="layer2">
       <div id="layer2-1"><h2>盒子2-1</h2></div>
       <div id="layer2-2"><h2>盒子2-2</h2></div>
       <div id="layer2-3"></div>
 </div>    

• CSS样式的定义顺序按照盒子的先后顺序写,先写layer1,再写layer2,layer2-1,layer2-2 ...

 <style type="text/css">         
      .layer1{width:100%; height:100px;  background:blue;}
      .layer2{width:100%; height:200px;}  
      .layer2-1{width:30%; height:200px; background:red;}  
      .layer2-2{width:70%; height:200px; background:orange;} 
      .layer3{width:100%; height:130px;  background:green;}  
 </style>