/* StudyCore 12 — Responsive Styles */

/* Tablet */
@media (max-width: 1024px) {
  .sidebar {
    transform: translateX(-100%);
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .main-content {
    margin-left: 0;
  }

  .menu-toggle {
    display: flex;
  }

  .search-results {
    left: 0;
  }

  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
}

/* Mobile */
@media (max-width: 640px) {
  :root {
    --font-size-base: 15px;
    --topbar-height: 52px;
  }

  .page-content {
    padding: 16px;
  }

  .topbar {
    padding: 0 12px;
  }

  .search-bar-container {
    max-width: 100%;
  }

  .dashboard-title {
    font-size: var(--text-2xl);
  }

  .cards-grid {
    grid-template-columns: 1fr;
  }

  .grid-2 { grid-template-columns: 1fr; }
  .grid-3 { grid-template-columns: 1fr; }
  .grid-4 { grid-template-columns: 1fr; }

  .mobile-nav {
    display: flex;
  }

  .main-content {
    padding-bottom: var(--mobile-nav-height);
  }

  .search-results {
    left: 0;
    top: var(--topbar-height);
    padding: 8px 12px 24px;
  }

  .chapter-nav-sticky {
    position: static;
    overflow-x: auto;
    flex-wrap: nowrap;
    -webkit-overflow-scrolling: touch;
    padding: 8px;
  }

  .generator-controls {
    flex-direction: column;
  }

  .generator-control {
    min-width: 100%;
  }

  .element-cell {
    min-width: 38px;
    font-size: 0.7rem;
  }

  .element-cell .atomic-num {
    font-size: 0.45rem;
  }

  .element-cell .symbol {
    font-size: 0.75rem;
  }

  .periodic-table {
    gap: 2px;
  }

  .element-panel {
    width: 100%;
    max-width: 100vw;
  }

  .chapter-detail-title {
    font-size: var(--text-xl);
  }

  .formula-expression {
    font-size: var(--text-lg);
  }

  .data-table {
    font-size: var(--text-xs);
  }

  .data-table th,
  .data-table td {
    padding: 8px 10px;
  }

  .solution-step {
    flex-direction: column;
    gap: 6px;
  }

  .settings-item {
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
  }

  .generator-actions {
    flex-direction: column;
  }

  .generator-actions .btn {
    width: 100%;
    justify-content: center;
  }
}

/* Large Desktop */
@media (min-width: 1400px) {
  .page-content {
    max-width: 1200px;
  }

  .periodic-table-container {
    overflow-x: visible;
  }
}

/* Mobile Nav - Hidden by default */
.mobile-nav {
  display: none;
}

@media (max-width: 640px) {
  .mobile-nav {
    display: flex;
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    height: var(--mobile-nav-height);
    background: var(--bg-primary);
    border-top: 1px solid var(--border-color);
    z-index: 100;
    align-items: center;
    justify-content: space-around;
    padding: 0 4px;
  }

  .mobile-nav-link {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2px;
    padding: 6px 8px;
    font-size: 0.625rem;
    font-weight: 500;
    color: var(--text-tertiary);
    transition: color var(--transition-fast);
    min-width: 0;
    flex: 1;
    text-align: center;
  }

  .mobile-nav-link.active {
    color: var(--text-primary);
  }

  .mobile-nav-link svg {
    width: 20px;
    height: 20px;
  }
}

/* Mobile More Menu */
.mobile-more-menu {
  position: fixed;
  inset: 0;
  z-index: 150;
}

.mobile-more-overlay {
  position: absolute;
  inset: 0;
  background: rgba(0,0,0,0.4);
}

.mobile-more-panel {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  background: var(--bg-primary);
  border-radius: var(--radius-lg) var(--radius-lg) 0 0;
  padding: 20px;
  max-height: 70vh;
  overflow-y: auto;
  animation: slideUp 0.3s ease;
}

@keyframes slideUp {
  from { transform: translateY(100%); }
  to { transform: translateY(0); }
}

.mobile-more-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
}

.mobile-more-header h3 {
  font-size: var(--text-lg);
  font-weight: 700;
}

.mobile-more-links {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.mobile-more-links a {
  display: block;
  padding: 12px;
  border-radius: var(--radius-sm);
  font-weight: 500;
  transition: background var(--transition-fast);
}

.mobile-more-links a:hover {
  background: var(--bg-secondary);
}

/* Print */
@media print {
  .sidebar, .mobile-nav, .topbar, .search-results {
    display: none !important;
  }

  .main-content {
    margin-left: 0 !important;
  }

  .page-content {
    padding: 0 !important;
  }
}