css中线作为基准线方法~
![css-center-line-as-a-baseline-method](http://blog.idea5.org/wp-content/uploads/2010/12/css-center-line-as-a-baseline-method-300x215.png)
.red{ margin:0 auto; }
.red{ margin:0 auto; }
.orange{ margin:-200px auto 0 auto; }
.red{ margin:0 auto;}
.orange{ position:relative; left:200px; margin:-200px auto 0 auto; }
.yellow{ position:relative; right:200px; margin:-200px auto 0 auto; }
.green{ position:relative; left:100px; margin:0 auto 0 auto; }
.blue{ position:relative; right:100px; margin:-200px auto 0 auto; }