CSS Grid

.gallery {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.feature {
  grid-column: span 2;
}
.sidebar {
  grid-row: span 2;
}

.layout {
  display: grid;
  grid-template-areas:
    "header header"
    "sidebar main"
    "footer footer";
}

.header  { grid-area: header; }
.sidebar { grid-area: sidebar; }
.main    { grid-area: main; }
.footer  { grid-area: footer; }

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}