html,
body {
  height: 100%;
}

body {
  display: grid;
  grid-template-columns: min-content 1fr;
  grid-template-rows: min-content 1fr;
  grid-template-areas:
    "sidebar header"
    "sidebar main"
}

#page-sidebar {
  grid-area: sidebar;
  width: 60px;
}

#page-header {
  grid-area: header;
  height: 60px;
}

#page-content {
  grid-area: main;
}