title: How to split a div into multiple rows and columns in css?
body: <p>I have div <code>subdiv</code> inside <code>maindiv</code>. I want to make the sub div into multiple rows and columns as below.</p>
  
  <p>How to divide the <code>subdiv</code> as below</p>
  
  <p><img src="https://i.stack.imgur.com/sSSNA.png" alt="enter image description here"></p>