/* App shell + navigation. */
.topbar {
  background: var(--surface);
  border-bottom: 1px solid var(--line);
  position: sticky;
  top: 0;
  z-index: 10;
}
.topbar-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: .75rem 1.25rem;
  display: flex;
  align-items: center;
  gap: 1.25rem;
}
.brand { font-weight: 700; letter-spacing: .02em; color: var(--ink); }
.brand span { color: var(--accent); }
.nav { display: flex; gap: 1rem; flex: 1; }
.nav a { color: var(--ink-soft); font-size: .92rem; }
.nav a.active, .nav a:hover { color: var(--ink); }

main { max-width: var(--maxw); margin: 0 auto; padding: 1.75rem 1.25rem 4rem; }
.row { display: flex; gap: var(--gap); flex-wrap: wrap; }
.between { display: flex; align-items: center; justify-content: space-between; gap: 1rem; }
.stack > * + * { margin-top: 1rem; }
.muted { color: var(--ink-soft); }
.center-screen {
  min-height: 100vh; display: grid; place-items: center; padding: 1.25rem;
}