@media (max-width: 1050px) {
  :root {
    --sidebar-width: 238px;
  }

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

  .metric:nth-child(3) {
    border-left: 0;
    border-top: 1px solid var(--line);
  }

  .metric:nth-child(4) {
    border-top: 1px solid var(--line);
  }

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

@media (max-width: 760px) {
  /* 手機：側欄收進「選單」；測試環境標籤換到頂列第二行 */
  .env-tag {
    width: 100%;
  }

  /* 手機的頂列固定在上方，標籤縮成一行；完整說明在「了解環境邊界」 */
  .env-tag span {
    display: none;
  }

  .app-shell {
    display: block;
  }

  .sidebar {
    box-shadow: 8px 0 30px rgba(14, 16, 21, 0.22);
    height: 100vh;
    left: 0;
    max-width: 86vw;
    position: fixed;
    top: 0;
    transform: translateX(-110%);
    transition: transform 180ms ease;
    width: 286px;
    z-index: 50;
  }

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

  .topbar {
    align-items: center;
    flex-wrap: wrap;
    gap: 12px;
    min-height: auto;
    padding: 13px 16px;
  }

  .mobile-menu {
    background: var(--surface);
    border: 1px solid var(--navy);
    color: var(--navy);
    display: inline-block;
    min-height: 44px;
    padding: 8px 12px;
  }

  .page-heading {
    flex: 1;
  }

  .page-heading .eyebrow {
    display: none;
  }

  .page-heading h1 {
    font-family: var(--font-sans);
    font-size: 20px;
  }

  #app-content {
    padding: 24px 16px 42px;
  }

  .section-intro {
    align-items: start;
    flex-direction: column;
  }

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

  .metric {
    min-height: 112px;
    padding: 16px 12px;
  }

  .metric b {
    font-size: 30px;
  }

  .metric small {
    font-size: 11px;
  }

  .panel {
    padding: 20px 14px;
  }

  .panel-head {
    align-items: start;
    flex-direction: column;
  }

  .score-options {
    grid-template-columns: 1fr;
  }

  .score-options label {
    justify-content: flex-start;
    padding: 0 14px;
  }

  .stepper {
    gap: 4px;
    grid-template-columns: 1fr;
  }

  .step {
    border-left: 3px solid var(--line);
    border-top: 0;
    padding: 8px 0 8px 13px;
  }

  .source-row {
    align-items: start;
    grid-template-columns: 1fr;
  }

  .split-summary {
    grid-template-columns: 1fr;
  }

  .action-bar {
    align-items: stretch;
    flex-direction: column-reverse;
  }

  .action-bar button {
    width: 100%;
  }

  /* 收尾步驟是有順序的（計算 → 檢核 → 定案），手機上照順序由上往下排 */
  .action-bar.closing-steps {
    flex-direction: column;
  }

  .dialog-panel {
    padding: 21px 18px;
  }
}

@media (max-width: 430px) {
  .secondary-button {
    width: 100%;
  }

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

  .metric + .metric,
  .metric:nth-child(3),
  .metric:nth-child(4) {
    border-left: 0;
    border-top: 1px solid var(--line);
  }

  .metric {
    min-height: 92px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}