<div class="wrapper">
  <div class="box a">A</div>
  <div class="box b">B</div>
  <div class="box c">C</div>
  <div class="box d">D</div>
</div>

body {
  margin: 40px;
}

.wrapper {
    display: grid;
    grid-gap: 10px;
    grid-template-columns: [col1-start] 100px  [col2-start] 100px  [col3-start] 100px [col3-end];
    grid-template-rows: [row1-start] auto [row2-start] auto [row2-end];
    background-color: #fff;
    color: #444;
  }

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

  }

  .a {
    grid-column: col1-start / col3-start;
    grid-row: row1-start ;
  }
  .b {
    grid-column: col3-start ;
    grid-row: row1-start / row2-end;
  }
  .c {
    grid-column: col1-start;
    grid-row: row2-start ;
  }
  .d {
    grid-column: col2-start ;
    grid-row: row2-start ;
  }