@media (max-width: 1024px) {
  .site-header {
    align-items: stretch;
    flex-direction: column;
  }

  .top-nav {
    justify-content: flex-start;
    overflow-x: auto;
    width: 100%;
    flex-wrap: nowrap;
    padding-bottom: 0.25rem;
    scrollbar-width: thin;
    border-top: 1px solid var(--line);
    margin-top: 0.1rem;
    padding-top: 0.45rem;
  }

  .top-nav a {
    white-space: nowrap;
  }

  .hero {
    grid-template-columns: 1fr;
    min-height: auto;
    padding-top: 2rem;
  }

  .progress-panel {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .tab-list {
    overflow-x: auto;
    flex-wrap: nowrap;
    padding-bottom: 0.2rem;
  }

  .tab-btn {
    white-space: nowrap;
  }

  .sorting-controls {
    grid-template-columns: 1fr 1.35fr;
  }

  .sorting-control-buttons .btn {
    min-height: 44px;
  }
}

@media (min-width: 721px) and (max-width: 1024px) {
  .lecture-dashboard-grid,
  .mini-grid,
  .code-grid,
  .practice-grid,
  .quiz-grid,
  .cheat-grid,
  .sorting-overview-grid,
  .sorting-cheat-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 720px) {
  .footer-grid {
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
  }

  .footer-brand {
    grid-column: 1 / -1;
  }

  .back-to-top {
    bottom: 1rem;
    right: 1rem;
    width: 2.5rem;
    height: 2.5rem;
  }

  .section {
    width: min(100% - 1rem, 1060px);
    padding: 2.35rem 0;
  }
}

  .site-header {
    padding: 0.75rem;
  }

  .brand {
    font-size: 1rem;
  }

  .top-nav a,
  .btn,
  .tab-btn,
  .choice {
    min-height: 44px;
    padding: 0.64rem 0.82rem;
    font-size: 0.9rem;
  }

  .hero {
    gap: 0.75rem;
  }

  .hero > div:first-child {
    padding: 1.25rem;
  }

  h1 {
    font-size: clamp(2.45rem, 15vw, 4rem);
  }

  .hero-meta li {
    width: auto;
    text-align: left;
  }

  .progress-panel {
    grid-template-columns: 1fr;
  }

  .section-jump-grid {
    grid-template-columns: 1fr 1fr;
  }

  .jump-row {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .jump-row .btn {
    width: 100%;
  }

  .chunk-card summary {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.25rem;
  }

  .control-row {
    flex-direction: column;
  }

  .control-row input,
  .control-row .btn {
    width: 100%;
  }

  .mini-grid,
  .code-grid,
  .practice-grid,
  .quiz-grid,
  .cheat-grid,
  .lecture-dashboard-grid,
  .algorithm-grid,
  .sorting-overview-grid,
  .sorting-cheat-grid {
    grid-template-columns: 1fr;
  }

  .lecture-card {
    min-height: auto;
  }

  .recognition-row {
    grid-template-columns: 1fr;
    gap: 0.25rem;
  }

  .big-o-viz {
    padding: 0.75rem;
  }

  .op-grid {
    grid-template-columns: repeat(5, minmax(0, 1fr));
  }

  .op-row span,
  .op-grid span,
  .halving-row span,
  .branch-tree span {
    min-width: 2.2rem;
    min-height: 2.2rem;
    font-size: 0.82rem;
  }

  .viz {
    min-height: 320px;
    overflow-x: auto;
  }

  .viz svg {
    width: 100%;
    height: auto;
  }

  .array-cell {
    min-width: 52px;
    min-height: 52px;
  }

  code {
    font-size: 0.82rem;
  }

  .sort-trace-card,
  .sort-example-block {
    padding: 0.85rem;
  }

  .trace-table {
    min-width: 620px;
  }

  .merge-level {
    grid-template-columns: 1fr;
    gap: 0.25rem;
  }

  .sort-cell {
    min-width: 2.05rem;
    min-height: 1.95rem;
    font-size: 0.78rem;
  }

  .sorting-controls {
    grid-template-columns: 1fr;
  }

  .sorting-controls label,
  .sorting-control-buttons {
    min-width: 0;
  }

  .sorting-control-buttons {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .sorting-control-buttons .btn {
    min-width: 0;
  }

  .sorting-control-buttons .btn:first-child {
    grid-column: 1 / -1;
  }

  .sorting-trace-status {
    align-items: flex-start;
  }

  .sorting-svg-wrap {
    min-height: 240px;
  }

  .sorting-trace-table {
    max-width: 100%;
    overflow-x: auto;
  }

  .sorting-trace-table table {
    min-width: 660px;
  }

  .sort-card-facts {
    gap: 0.5rem;
  }

  .tab-list,
  .array-row,
  .trace-table-wrap,
  .sorting-trace-table {
    -webkit-overflow-scrolling: touch;
  }
}

@media (max-width: 520px) {
  .sorting-visualizer-panel {
    padding: 0.85rem;
  }

  .sorting-legend {
    width: 100%;
  }

  .trace-pill {
    flex: 1 1 calc(50% - 0.45rem);
    justify-content: center;
  }

  .sorting-step-explanation {
    padding: 0.82rem 0.85rem;
  }

  .sorting-control-buttons {
    grid-template-columns: 1fr;
  }

  .sorting-control-buttons .btn {
    width: 100%;
  }
}

@media (max-width: 480px) {
  .footer-grid {
    grid-template-columns: 1fr;
  }

  .footer-brand {
    grid-column: auto;
  }
}

@media (max-width: 480px) {
  body {
    line-height: 1.55;
  }

  .site-header {
    gap: 0.65rem;
    padding: 0.6rem;
  }

  .top-nav {
    gap: 0.35rem;
  }

  .top-nav a,
  .btn,
  .tab-btn,
  .choice {
    min-height: 44px;
  }

  .section {
    width: min(100% - 0.8rem, 1180px);
    padding: 1.85rem 0;
  }

  .compact-section {
    padding-top: 0;
  }

  .section-heading {
    margin-bottom: 0.9rem;
  }

  h2 {
    font-size: 1.42rem;
  }

  h3 {
    font-size: 1rem;
  }

  .lead {
    font-size: 0.98rem;
  }

  .section-jump-grid,
  .sorting-overview-grid,
  .sorting-cheat-grid {
    grid-template-columns: 1fr;
  }

  .jump-row,
  .sorting-control-buttons {
    grid-template-columns: 1fr;
  }

  .hero-meta li {
    width: 100%;
  }

  .progress-panel {
    gap: 0.55rem;
  }

  .chunk-body,
  .code-card,
  .practice-card,
  .quiz-card,
  .cheat-card,
  .algorithm-card,
  .method-card,
  .image-card,
  .lecture-card,
  .sorting-overview-card {
    padding: 0.9rem;
  }

  .lab-shell {
    padding: 0.65rem;
  }

  .trace-table {
    min-width: 520px;
  }

  .sorting-trace-table table {
    min-width: 520px;
  }

  .sorting-svg-wrap {
    min-height: 220px;
  }
}

@media (max-width: 420px) {
  .section {
    width: min(100% - 0.75rem, 1180px);
  }

  .hero-meta {
    gap: 0.45rem;
  }

  .hero-meta li {
    width: 100%;
    text-align: center;
  }

  .jump-row .btn {
    flex: 1 1 100%;
  }

  .viz {
    min-height: 280px;
  }

  .trace-pill {
    flex-basis: 100%;
  }
}

@media (max-width: 360px) {
  .section {
    width: min(100% - 0.6rem, 1180px);
  }

  .hero > div:first-child,
  .sorting-visualizer-panel {
    padding: 0.75rem;
  }

  .top-nav a,
  .btn,
  .tab-btn,
  .choice {
    font-size: 0.84rem;
    padding-inline: 0.68rem;
  }

  .sort-cell {
    min-width: 1.9rem;
  }
}