.not-found {
  min-height: 80vh;
  display: flex; align-items: center; justify-content: center;
  text-align: center;
  padding-top: calc(var(--header-height) + var(--topbar-height));
}
.not-found h1 { font-size: 72px; color: var(--color-primary); font-weight: 700; margin: 16px 0 4px; }
.not-found h2 { font-size: 20px; margin-bottom: 10px; }
.not-found p { color: var(--color-text-light); margin-bottom: 28px; }