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

body {
  display: grid;
  grid-template-rows: auto 1fr auto;
  grid-template-columns: auto 1fr 1fr;
  grid-template-areas: "header header header" "sidebar content content" "footer footer footer";
  min-height: 100vh;
}
header,
aside,
main,
footer {
  border: 1px solid;
  padding: 1rem;
  text-align: center;
}

header {
  grid-area: header;
  padding: 1.5rem 1rem;
}

aside {
  grid-area: sidebar;
  width: 140px;
}
main {
  grid-area: content;
}
footer {
  grid-area: footer;
}