body {
    overflow: hidden;
    margin: 0;
  }

  .container {
    display: grid;
    grid-template-columns: 1fr;
    grid-template-rows: 80px 1fr;
    grid-auto-rows: 1fr;
    gap: 0px 0px;
    grid-auto-flow: row;
    grid-template-areas:
      "Header"
      "Body";
  }

  .Header {
    grid-area: Header;
    background-color: red;
  }

  .Body {
    display: grid;
    grid-template-columns: 1fr;
    grid-template-rows: 60px 1fr;
    gap: 0px 0px;
    grid-auto-flow: row;
    grid-template-areas:
      "Tabs"
      "Grid";
    grid-area: Body;
    background-color: green;
  }

  .Tabs {
    grid-area: Tabs;
    background-color: pink;
  }

  .Grid {
    grid-area: Grid;
    background-color: yellow;
  }

<div class="container">
  <div class="Header">Header</div>
  <div class="Body">
    <div class="Tabs">Tabs</div>
    <div class="Grid">
      <div class="scrollable">
        <p>1</p>
        <p>1</p>
        <p>1</p>
        <p>1</p>
        <p>1</p>
        <p>1</p>
        <p>1</p>
        <p>1</p>
        <p>1</p>
        <p>1</p>
        <p>1</p>
        <p>1</p>
        <p>1</p>
        <p>1</p>
        <p>1</p>
        <p>1</p>
      </div>
    </div>
  </div>
</div>