jqeury-easyui-layout problem solution_jquery

Today when I was using easyui to make layout, I encountered a confusing problem.

Problem: When class="easyui-layout" is written in an independent div, the layout style cannot be displayed and no error is reported.

For example:

Copy code The code is as follows:

Display:

Solution: When class="easyui-layout" is written in the body, the problem is solved. And the region attribute cannot be included by other unrelated divs.

Code:

Copy code The code is as follows:

Always wondering why?