.app-header {
  position: fixed;
  inset: 0 0 auto;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: calc(var(--header-height) + env(safe-area-inset-top));
  padding: env(safe-area-inset-top) var(--space-4) 0;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
}

.app-title {
  font-weight: 700;
  letter-spacing: 0.02em;
}

.app-main {
  max-width: var(--content-width);
  margin: 0 auto;
  padding:
    calc(var(--header-height) + env(safe-area-inset-top) + var(--space-5))
    var(--space-4)
    calc(var(--tabbar-height) + env(safe-area-inset-bottom) + var(--space-5));
}

.sandbox .app-main {
  padding-top: calc(var(--header-height) + var(--sandbox-height) + env(safe-area-inset-top) + var(--space-5));
}

.tabbar {
  position: fixed;
  inset: auto 0 0;
  z-index: 10;
  display: grid;
  grid-template-columns: 1fr 1fr;
  height: calc(var(--tabbar-height) + env(safe-area-inset-bottom));
  padding-bottom: env(safe-area-inset-bottom);
  background: var(--surface);
  border-top: 1px solid var(--border);
}

.tabbar a {
  display: grid;
  place-items: center;
  color: var(--text-muted);
  text-decoration: none;
  font-weight: 600;
}

.tabbar a[aria-current="page"] {
  color: var(--accent);
}

.stack {
  display: grid;
  gap: var(--space-4);
}