<!DOCTYPE html>
<html>
  <head>
    <title>Example 31</title>
    <meta charset="utf-8">
    <style>
    body {
  margin: 40px;
}

.wrapper {
  display: grid;
  grid-gap: 10px;
  grid-template-columns: minmax(200px, 1fr) 200px 200px;
  background-color: #fff;
  color: #444;
}

.box {
  background-color: #444;
  color: #fff;
  border-radius: 5px;
  padding: 20px;
  font-size: 150%;
}



   </style>
</head>

 <body>

   <div class="wrapper">
     <div class="box a">A</div>
    <div class="box b">B</div>
    <