タイトル

<header><h1>タイトル</h1></header>
<main>メイン</main>
<nav>ナビ</nav>
<aside id="side">サイド</aside>
<aside id="ad">広告</aside>
<footer>フッター</footer>

body {
  display: grid;
  grid-template-areas:
    "title  title  title"
    "nav    main   side"
    "ad     main   side"
    "footer footer footer";
  grid-template-columns: 80px 1fr 300px;
  grid-template-rows: 70px auto 1fr 80px;
  min-height: 100vh;
}

header { grid-area: title; }
main   { grid-area: main; }
nav    { grid-area: nav; }
#ad    { grid-area: ad; }
#side  { grid-area: side; }
footer { grid-area: footer; }