.dt-page { padding-top: 18px; }
.dt-crumbs {
  display: flex;
  gap: 7px;
  margin-bottom: 12px;
  color: var(--text-tertiary);
  font-size: 0.72rem;
  overflow: hidden;
  white-space: nowrap;
}
.dt-crumbs a { color: inherit; text-decoration: none; }
.dt-hero { margin-bottom: 22px; overflow: hidden; }
.dt-hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 250px;
  gap: 18px;
  align-items: stretch;
}
.dt-kicker { color: var(--primary); font-size: 0.72rem; font-weight: 800; }
.dt-title {
  margin: 5px 0 0;
  color: var(--text);
  font-size: clamp(1.25rem, 2.4vw, 1.72rem);
  font-weight: 800;
  line-height: 1.25;
}
.dt-desc {
  margin: 8px 0 0;
  color: var(--text-secondary);
  font-size: 0.82rem;
  line-height: 1.65;
}
.dt-tags, .dt-actions, .dt-meta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
  margin-top: 12px;
}
.dt-pill {
  display: inline-flex;
  align-items: baseline;
  gap: 3px;
  padding: 6px 9px;
  border-radius: 10px;
  background: var(--surface-variant, #f1f5f9);
  color: var(--text-tertiary);
  font-size: 0.7rem;
  line-height: 1;
}
.dt-pill strong { color: var(--text); font-size: 0.82rem; }
.dt-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 7px;
  min-height: 40px;
  padding: 0 14px;
  border: 1px solid var(--border-light);
  border-radius: 13px;
  background: var(--surface);
  color: var(--text);
  font-size: 0.78rem;
  font-weight: 800;
  text-decoration: none;
  cursor: pointer;
}
.dt-btn.primary { border-color: var(--primary); background: var(--primary); color: #fff; }
.dt-btn.success { border-color: var(--success-50); background: var(--success-50); color: var(--success-text); }
.dt-btn.is-active { border-color: var(--primary-border); background: var(--primary-50); color: var(--primary); }
.dt-action-note { min-height: 18px; margin-top: 5px; color: var(--primary); font-size: 0.7rem; }
.dt-pill-alert strong { color: var(--error); }
.dt-pill-hot strong { color: #b45309; }
.dt-side {
  display: grid;
  gap: 10px;
}
.dt-mastery {
  display: grid;
  place-items: center;
  min-height: 108px;
}
.dt-ring {
  width: 88px;
  height: 88px;
  border-radius: 50%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: radial-gradient(circle at center, #fff 0 58%, transparent 59%), conic-gradient(var(--primary) 0 var(--mastery, 0%), #dbeafe var(--mastery, 0%) 100%);
  color: var(--primary);
}
.dt-ring strong { font-size: 1.28rem; line-height: 1.05; }
.dt-ring span { margin-top: 3px; font-size: 0.58rem; font-weight: 700; color: var(--text-tertiary); }
.dt-side-list { display: grid; gap: 8px; }
.dt-side-item {
  display: flex;
  justify-content: space-between;
  gap: 10px;
  padding: 9px 10px;
  border: 1px solid var(--border-light);
  border-radius: 12px;
  background: var(--surface);
  color: var(--text-secondary);
  font-size: 0.72rem;
}
.dt-side-item strong { color: var(--text); font-size: 0.78rem; }
.dt-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 250px;
  gap: 16px;
  align-items: start;
}
.dt-article {
  overflow: hidden;
  padding: 0;
}
.dt-section {
  padding: 22px;
  border-bottom: 1px solid var(--border-light);
}
.dt-section:last-child { border-bottom: none; }
.dt-section-head {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  margin-bottom: 14px;
}
.dt-mark {
  width: 30px;
  height: 30px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex: 0 0 auto;
  background: var(--primary);
  color: #fff;
  font-size: 0.82rem;
  font-weight: 800;
}
.dt-mark.green { background: var(--success); }
.dt-mark.amber { background: var(--warning); }
.dt-mark.red { background: var(--error); }
.dt-section-title {
  margin: 0;
  color: var(--text);
  font-size: 1rem;
  font-weight: 800;
  line-height: 1.35;
}
.dt-section-sub {
  margin: 3px 0 0;
  color: var(--text-secondary);
  font-size: 0.74rem;
  line-height: 1.55;
}
.dt-memory-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 10px;
}
.dt-memory {
  min-height: 112px;
  padding: 14px;
  border: 1px solid var(--border-light);
  border-radius: 14px;
  background: var(--surface-variant, #f1f5f9);
}
.dt-memory strong { display: block; color: var(--text); font-size: 0.82rem; }
.dt-memory span { display: block; margin-top: 5px; color: var(--text-secondary); font-size: 0.7rem; line-height: 1.55; }
.dt-formula {
  padding: 16px;
  border: 1px solid var(--primary-border);
  border-radius: 14px;
  background: var(--primary-50);
  color: #1e3a8a;
  font-family: Consolas, Monaco, monospace;
  font-size: 0.86rem;
  font-weight: 800;
  line-height: 1.8;
}
.dt-token {
  display: inline-flex;
  padding: 4px 8px;
  border: 1px solid var(--primary-border);
  border-radius: 8px;
  background: #fff;
}
.dt-copy {
  color: var(--text-secondary);
  font-size: 0.82rem;
  line-height: 1.9;
}
.dt-copy p + p { margin-top: 8px; }
.dt-usage-list { display: grid; gap: 10px; }
.dt-usage {
  padding: 12px 14px;
  border-left: 3px solid var(--primary-border);
  border-radius: 12px;
  background: #fbfdff;
}
.dt-usage h3 { margin: 0 0 4px; color: var(--text); font-size: 0.86rem; }
.dt-usage p { margin: 0; color: var(--text-secondary); font-size: 0.76rem; line-height: 1.65; }
.dt-example {
  border: 1px solid var(--border-light);
  border-radius: 14px;
  overflow: hidden;
  background: #fff;
}
.dt-example + .dt-example { margin-top: 10px; }
.dt-example-en { padding: 13px 14px 5px; color: var(--text); font-weight: 800; font-size: 0.82rem; }
.dt-example-index {
  display: inline-grid;
  place-items: center;
  width: 22px;
  height: 22px;
  margin-right: 8px;
  border-radius: 7px;
  background: var(--primary-50);
  color: var(--primary);
  font-size: 0.68rem;
}
.dt-example-tag {
  float: right;
  margin-left: 8px;
  color: var(--text-tertiary);
  font-size: 0.66rem;
  font-weight: 700;
}
.dt-example-cn { padding: 0 14px 10px; color: var(--text-secondary); font-size: 0.74rem; }
.dt-example-note {
  padding: 9px 14px;
  border-top: 1px solid var(--border-light);
  background: var(--primary-50);
  color: var(--primary);
  font-size: 0.72rem;
}
.dt-table-wrap { overflow-x: auto; border: 1px solid var(--border-light); border-radius: 14px; }
.dt-table { width: 100%; min-width: 560px; border-collapse: collapse; }
.dt-table th {
  padding: 11px 12px;
  background: var(--surface-variant, #f1f5f9);
  color: var(--text-tertiary);
  font-size: 0.72rem;
  text-align: left;
}
.dt-table td {
  padding: 12px;
  border-top: 1px solid var(--border-light);
  color: var(--text-secondary);
  font-size: 0.76rem;
  vertical-align: top;
}
.dt-mistake {
  display: grid;
  grid-template-columns: 1fr 1fr;
  border: 1px solid var(--border-light);
  border-radius: 14px;
  overflow: hidden;
}
.dt-mistake + .dt-mistake { margin-top: 10px; }
.dt-bad, .dt-good { padding: 12px; font-size: 0.76rem; line-height: 1.6; }
.dt-bad { background: var(--error-50); color: #991b1b; }
.dt-good { background: var(--success-50); color: #065f46; }
.dt-why {
  grid-column: 1 / -1;
  padding: 10px 12px;
  border-top: 1px solid var(--border-light);
  background: #fbfdff;
  color: var(--text-secondary);
  font-size: 0.72rem;
}
.dt-collocation-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 9px;
}
.dt-collocation {
  display: grid;
  gap: 3px;
  padding: 11px 12px;
  border: 1px solid var(--border-light);
  border-radius: 12px;
  background: #fbfdff;
}
.dt-collocation strong { color: var(--text); font-size: 0.78rem; line-height: 1.45; }
.dt-collocation span { color: var(--text-secondary); font-size: 0.7rem; line-height: 1.45; }
.dt-tip-list { display: grid; gap: 9px; }
.dt-tip {
  padding: 12px 14px;
  border-left: 3px solid var(--primary-border);
  border-radius: 12px;
  background: var(--primary-50);
}
.dt-tip.warn { border-left-color: #f59e0b; background: #fffbeb; }
.dt-tip.danger { border-left-color: var(--error); background: var(--error-50); }
.dt-tip strong { display: block; color: var(--text); font-size: 0.8rem; }
.dt-tip p { margin: 4px 0 0; color: var(--text-secondary); font-size: 0.74rem; line-height: 1.65; }
.dt-mnemonic {
  display: grid;
  gap: 8px;
  padding: 16px;
  border: 1px solid var(--primary-border);
  border-radius: 14px;
  background: var(--primary-50);
}
.dt-mnemonic > span { color: var(--primary); font-size: 0.7rem; font-weight: 800; }
.dt-mnemonic > strong { color: var(--text); font-size: 0.86rem; line-height: 1.7; }
.dt-mnemonic > div { padding-top: 9px; border-top: 1px solid var(--primary-border); }
.dt-mnemonic b { color: var(--text); font-size: 0.76rem; }
.dt-mnemonic p { margin: 4px 0 0; color: var(--text-secondary); font-size: 0.72rem; line-height: 1.65; }
.dt-practice {
  padding: 16px;
  border: 1px solid var(--border-light);
  border-radius: 14px;
  background: #fbfdff;
}
.dt-practice-question { color: var(--text); font-size: 0.86rem; font-weight: 800; line-height: 1.65; }
.dt-practice-options { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 8px; margin-top: 12px; }
.dt-practice-option {
  min-height: 42px;
  padding: 9px 11px;
  border: 1px solid var(--border-light);
  border-radius: 11px;
  background: var(--surface);
  color: var(--text-secondary);
  font-size: 0.76rem;
  text-align: left;
  cursor: pointer;
}
.dt-practice-option:hover { border-color: var(--primary-border); color: var(--primary); }
.dt-practice-option.is-correct { border-color: #86efac; background: var(--success-50); color: #065f46; }
.dt-practice-option.is-wrong { border-color: #fecaca; background: var(--error-50); color: #991b1b; }
.dt-practice-result { margin-top: 10px; padding: 10px 12px; border-radius: 10px; background: var(--primary-50); color: var(--text-secondary); font-size: 0.74rem; line-height: 1.65; }
.dt-loading, .dt-error { padding: 52px 20px; text-align: center; }
.dt-loading strong, .dt-error strong { display: block; color: var(--text); font-size: 1rem; }
.dt-loading p, .dt-error p, .dt-empty-copy { margin: 8px 0 0; color: var(--text-secondary); font-size: 0.78rem; line-height: 1.65; }
.dt-section-toggle { display: none; }
.dt-rail {
  display: grid;
  gap: 14px;
  position: sticky;
  top: 76px;
}
.dt-rail-card {
  padding: 16px;
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  background: var(--surface);
  box-shadow: var(--shadow-sm);
}
.dt-rail-title { color: var(--text); font-size: 0.9rem; font-weight: 800; }
.dt-related { display: grid; gap: 8px; margin-top: 12px; }
.dt-related a {
  display: block;
  padding: 10px;
  border: 1px solid var(--border-light);
  border-radius: 12px;
  color: inherit;
  text-decoration: none;
}
.dt-related strong { display: block; color: var(--text); font-size: 0.78rem; }
.dt-related span { display: block; margin-top: 2px; color: var(--text-tertiary); font-size: 0.68rem; }
.dt-materials { border-color: var(--primary-border); background: var(--primary-50); }
.dt-materials p { margin: 8px 0 0; color: var(--text-secondary); font-size: 0.74rem; line-height: 1.6; }
.dt-materials-link { display: inline-flex; margin-top: 10px; color: var(--primary); font-size: 0.72rem; font-weight: 800; text-decoration: none; }
@media (max-width: 860px) {
  .dt-hero-grid, .dt-layout { grid-template-columns: 1fr; }
  .dt-side { grid-template-columns: 120px minmax(0, 1fr); }
  .dt-rail { position: static; grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 520px) {
  .dt-page { padding-top: 12px; }
  .dt-rail, .dt-memory-grid, .dt-collocation-grid, .dt-practice-options { grid-template-columns: 1fr; }
  .dt-side { grid-template-columns: 64px minmax(0, 1fr); align-items: center; gap: 8px; }
  .dt-title { font-size: 1.18rem; }
  .dt-desc { font-size: 0.78rem; }
  .dt-actions .dt-btn { flex: 1; min-width: 0; }
  .dt-mastery { min-height: 64px; }
  .dt-ring { width: 64px; height: 64px; }
  .dt-ring strong { font-size: 0.92rem; }
  .dt-ring span { margin-top: 2px; font-size: 0.5rem; }
  .dt-side-list { gap: 5px; }
  .dt-side-item { padding: 7px 9px; }
  .dt-section { padding: 18px 14px; }
  .dt-memory { min-height: 0; }
  .dt-mistake { grid-template-columns: 1fr; }
  .dt-why { grid-column: auto; }
  .dt-collapsible:not(.is-expanded) .dt-mobile-extra { display: none; }
  .dt-section-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    width: 100%;
    min-height: 38px;
    margin-top: 12px;
    border: 0;
    border-top: 1px solid var(--border-light);
    background: transparent;
    color: var(--primary);
    font-size: 0.72rem;
    font-weight: 800;
    cursor: pointer;
  }
  .dt-section-toggle .dt-chevron { font-size: 0.9rem; transition: transform 160ms ease; }
  .dt-section-toggle[aria-expanded="true"] .dt-chevron { transform: rotate(180deg); }
}