<section>
  <div class="container">
    <header>Header</header>
    <main>Main</main>
    <aside>Sidebar</aside>
    <footer>Footer</footer>
  </div>
</section>
@import url("https://fonts.googleapis.com/css2?family=Exo:wght@600&display=swap");

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  width: 100vw;
  min-height: 100vh;

  display: flex;
  justify-content: center;
  flex-direction: column;
  gap: 20px;
  font-family: "Exo", Arial, sans-serif;
  background-color: #f7f7f7;

  padding: 20px;
}

section {
  max-width: 80vw;
  width: 100%;
  margin: 0 auto;
  min-height: calc(80vh - 40px);
  display: flex;
  justify-content: center;
}

.container {
  border: 1px dashed #f36;
  box-shadow: 0 0 0 6px rgb(0 0 0 / 13%);
  border-radius: 1px;
}

.container > * {
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 10px;
  gap: 5px;
  color: #fff;
  font-size: 1.2rem;
  text-shadow: 1px 1px 0 rgb(0 0 0 / 0.5);
}

header {
  background-color: #f1c2c6;
}

aside {
  background-color: #dac2f1;
}

main {
  background-color: #ccf1c2;
}

footer {
  background-color: #c2e9f1;
}

.container {
  display: grid;
  grid-template-columns: [hd-col-start sb-col-start ft-col-start] 200px [sb-col-end mn-col-start] 1fr [hd-col-end mn-col-end ft-col-end];
  grid-template-rows: [hd-row-start] 80px [hd-row-end sb-row-start] 1fr [sb-row-end ft-row-start] 60px [ft-row-end];
  grid-gap: 1rem;
  width: 100%;

  grid-template-areas:
    "header   header"
    "sidebar  main"
    "footer   footer";

  transition: all 0.2s linear;
}

header {
  /* ①:  grid-area: header; */
  /* ②: grid-area: header-start / header-start / header-end / header-end; */
  grid-row: header-start / header-end;
  grid-column: header-start / header-end;
}
aside {
  /* ①: grid-area: sidebar;   */
  /* ②: grid-area: sidebar-start / sidebar-start / sidebar-end / sidebar-end; */
  grid-row: sidebar-start / sidebar-end;
  grid-column: sidebar-start / sidebar-end;
}
main {
  /* ①: grid-area: main;   */
  /* ②: grid-area: main-start / main-start / main-end / main-end; */
  grid-rows: main-start / main-end;
  grid-column: main-start / main-end;
}
footer {
  /* ①:  grid-area: footer; */
  /* ②: grid-area: footer-start / footer-start / footer-end / footer-end; */
  grid-rows: footer-start / footer-end;
  grid-column: footer-start / footer-end;
}

External CSS

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External JavaScript

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