DIV内嵌CSS：
<div style="width:98%;margin:auto;">
<div style="width:30%;height:300px;background-color:rgb(145, 176, 145);float:left;">111</div>
<div style="width:40%;height:300px;background-color:rgb(118, 118, 221);float:left;">222</div>
<div style="width:30%;height:300px;background-color:rgb(165, 100, 100);float:right;">333</div>
</div>
DIV居中:style="width:90%;margin:auto;"
111
222
333
CSS方式写法：https://blog.csdn.net/weixin_32309879/article/details/117859974
