/* ============================================================
   StudyHub Layout – Header, Bottom Nav, Drawer, Containers
   ============================================================ */

/* ── Container ── */
.container {
  width: 100%;
  max-width: var(--max-content-width);
  margin: 0 auto;
  padding: 0 var(--space-4);
}

/* ── App Header ── */
.app-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background: var(--bg-card);
  display: flex;
  align-items: center;
  padding: 0 var(--space-4);
  z-index: var(--z-fixed);
  box-shadow: var(--shadow-xs);
  gap: var(--space-3);
}

.app-header.transparent {
  background: transparent;
  box-shadow: none;
}

.app-header.dark {
  background: var(--gray-900);
  color: white;
}

.app-header.dark .header-title {
  color: white;
}

.header-back {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-full);
  transition: background var(--transition-fast);
  color: var(--text-primary);
  flex-shrink: 0;
}

.header-back:hover {
  background: var(--gray-100);
}

.app-header.dark .header-back {
  color: white;
}

.app-header.dark .header-back:hover {
  background: rgba(255,255,255,0.1);
}

.header-content {
  flex: 1;
  min-width: 0;
}

.header-title {
  font-size: var(--text-lg);
  font-weight: var(--font-bold);
  color: var(--text-primary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.header-subtitle {
  font-size: var(--text-xs);
  color: var(--text-tertiary);
  margin-top: -2px;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  flex-shrink: 0;
}

/* ── Bottom Navigation ── */
.bottom-nav {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  height: var(--bottom-nav-height);
  background: var(--bg-card);
  display: flex;
  align-items: center;
  justify-content: space-around;
  z-index: var(--z-fixed);
  box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.06);
  padding-bottom: env(safe-area-inset-bottom, 0px);
}

.nav-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2px;
  padding: var(--space-1) var(--space-3);
  color: var(--text-tertiary);
  text-decoration: none;
  font-size: 11px;
  font-weight: var(--font-medium);
  transition: color var(--transition-fast);
  min-width: 64px;
  min-height: 44px;
  position: relative;
  cursor: pointer;
  border-radius: var(--radius-sm);
}

.nav-item:hover {
  color: var(--primary);
}

.nav-item.active {
  color: var(--primary);
}

.nav-item.active .nav-icon {
  background: var(--primary-50);
  border-radius: var(--radius-full);
  padding: 2px 12px;
}

.nav-item svg {
  width: 22px;
  height: 22px;
}

.nav-item .nav-badge {
  position: absolute;
  top: 2px;
  right: 12px;
  width: 8px;
  height: 8px;
  background: var(--error-500);
  border-radius: 50%;
  border: 2px solid var(--bg-card);
}

/* ── Side Drawer ── */
.drawer-overlay {
  position: fixed;
  inset: 0;
  background: var(--bg-overlay);
  z-index: var(--z-drawer);
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-normal);
}

.drawer-overlay.active {
  opacity: 1;
  visibility: visible;
}

.drawer {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  width: var(--drawer-width);
  max-width: 85vw;
  background: var(--bg-card);
  z-index: calc(var(--z-drawer) + 1);
  transform: translateX(-100%);
  transition: transform var(--transition-normal);
  display: flex;
  flex-direction: column;
  overflow-y: auto;
}

.drawer.active {
  transform: translateX(0);
}

.drawer-header {
  padding: var(--space-5) var(--space-4);
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--border-light);
}

.drawer-logo {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--text-xl);
  font-weight: var(--font-bold);
  color: var(--primary);
}

.drawer-logo svg {
  width: 28px;
  height: 28px;
}

.drawer-close {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-full);
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}

.drawer-close:hover {
  background: var(--gray-100);
  color: var(--text-primary);
}

.drawer-nav {
  flex: 1;
  padding: var(--space-3) var(--space-2);
}

.drawer-item {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-4);
  font-size: var(--text-base);
  font-weight: var(--font-medium);
  color: var(--text-secondary);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  cursor: pointer;
  text-decoration: none;
  min-height: 44px;
}

.drawer-item:hover {
  background: var(--gray-50);
  color: var(--text-primary);
}

.drawer-item.active {
  background: var(--primary-50);
  color: var(--primary);
  font-weight: var(--font-semibold);
}

.drawer-item svg {
  width: 20px;
  height: 20px;
  flex-shrink: 0;
}

.drawer-footer {
  padding: var(--space-4);
  margin-top: auto;
}

.drawer-promo {
  background: linear-gradient(135deg, var(--primary-50), var(--primary-100));
  border-radius: var(--radius-lg);
  padding: var(--space-4);
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.drawer-promo-icon {
  width: 48px;
  height: 48px;
  flex-shrink: 0;
}

.drawer-promo-title {
  font-size: var(--text-sm);
  font-weight: var(--font-bold);
  color: var(--primary-800);
}

.drawer-promo-text {
  font-size: var(--text-xs);
  color: var(--primary-600);
  margin-bottom: 0;
}

/* ── Section ── */
.section {
  padding: var(--space-5) 0;
}

.section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-4);
  padding: 0 var(--space-4);
}

.section-title {
  font-size: var(--text-lg);
  font-weight: var(--font-bold);
  color: var(--text-primary);
}

.section-link {
  font-size: var(--text-sm);
  font-weight: var(--font-semibold);
  color: var(--primary);
  display: flex;
  align-items: center;
  gap: var(--space-1);
  cursor: pointer;
}

/* ── Grid Layouts ── */
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-3);
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-3);
}

.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-3);
}

/* ── Horizontal scroll ── */
.scroll-row {
  display: flex;
  gap: var(--space-3);
  overflow-x: auto;
  padding: var(--space-1) var(--space-4);
  scroll-snap-type: x mandatory;
  scrollbar-width: none;
}

.scroll-row::-webkit-scrollbar { display: none; }

.scroll-row > * {
  scroll-snap-align: start;
  flex-shrink: 0;
}

/* ── Safe area padding for iOS ── */
@supports (padding-bottom: env(safe-area-inset-bottom)) {
  .bottom-nav {
    padding-bottom: env(safe-area-inset-bottom);
    height: calc(var(--bottom-nav-height) + env(safe-area-inset-bottom));
  }
  
  .page-content {
    padding-bottom: calc(var(--bottom-nav-height) + env(safe-area-inset-bottom) + var(--space-4));
  }
}