     [content-row-start] "sidebar . content" 1fr [content-row-end]
    / 100px 100px 1fr;
  }

  .named-rows-and-columns {
    grid-template-columns: 100px 100px 1fr;
    grid-template-rows: [header-row-start] 100px [header-row-end content-row-start] 1fr [content-row-end];
    grid-template-areas: "header header header" "sidebar . content";
  }

  .header {
    grid-area: header;
  }

  .sidebar {
    grid-area: sidebar;
  }

  .content {
    grid-area: content;
  }

  .footer {
    grid-area: footer;
  }
<