/* ============================================================================
   UniCircle — layout.css
   App shell: left rail on desktop (syllabus-spine), bottom tab bar on mobile.
   ========================================================================= */

.app-shell {
  display: grid;
  grid-template-columns: var(--rail-width) 1fr;
  min-height: 100vh;
}

/* ---------- Desktop rail nav ---------- */

.rail {
  position: sticky;
  top: 0;
  height: 100vh;
  border-right: 1px solid var(--line);
  padding: var(--space-5) var(--space-4);
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
}

.rail-brand {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-display);
  font-weight: 700;
  font-size: var(--text-lg);
}

.rail-brand .dot { color: var(--cobalt); }

.rail-nav {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  list-style: none;
  margin: 0;
  padding: 0;
}

.rail-link {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-3);
  border-radius: var(--radius-md);
  color: var(--ink-soft);
  font-weight: 500;
  font-size: var(--text-sm);
}

.rail-link:hover { background: var(--paper-dim); text-decoration: none; }

.rail-link.active {
  background: var(--cobalt-dim);
  color: var(--cobalt);
}

.rail-footer {
  margin-top: auto;
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.main {
  padding: var(--space-6) var(--space-6) var(--space-8);
  min-width: 0;
}

/* ---------- Mobile tab bar ---------- */

.tab-bar {
  display: none;
}

@media (max-width: 860px) {
  .app-shell { grid-template-columns: 1fr; }
  .rail { display: none; }
  .main { padding: var(--space-4) var(--space-4) calc(var(--space-8) + 56px); }

  .tab-bar {
    display: flex;
    justify-content: space-around;
    align-items: center;
    position: fixed;
    bottom: 0; left: 0; right: 0;
    height: 64px;
    background: var(--paper);
    border-top: 1px solid var(--line);
    z-index: 40;
    padding-bottom: env(safe-area-inset-bottom);
  }

  .tab-link {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2px;
    font-size: 10px;
    color: var(--slate);
    font-weight: 500;
  }

  .tab-link.active { color: var(--cobalt); }
  .tab-link:hover { text-decoration: none; }
}

/* ---------- Unauthenticated pages (landing/login/signup) ---------- */

.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-5) 0;
}

.auth-shell {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: var(--space-5);
}

.auth-card {
  width: 100%;
  max-width: 400px;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  box-shadow: var(--shadow-card);
}

/* ---------- Generic responsive grid for cards ---------- */

.grid {
  display: grid;
  gap: var(--space-5);
}

.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }

@media (max-width: 860px) {
  .grid-2, .grid-3 { grid-template-columns: 1fr; }
}