:root {
  --hub-bg: #ffffff;
  --hub-surface: #ffffff;
  --hub-surface-soft: #f8fafc;
  --hub-border: #e2e8f0;
  --hub-border-strong: rgba(37, 99, 235, 0.28);
  --hub-text: #0f172a;
  --hub-muted: #475569;
  --hub-subtle: #64748b;
  --hub-accent: #2563eb;
  --hub-accent-strong: #1d4ed8;
  --hub-radius: 14px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  color-scheme: light;
}

body {
  margin: 0;
  min-height: 100dvh;
  font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei UI", system-ui, sans-serif;
  color: var(--hub-text);
  background: var(--hub-bg);
}

button,
input,
a {
  font: inherit;
}

a {
  color: inherit;
  text-decoration: none;
}

button {
  border: 0;
  background: transparent;
  cursor: pointer;
}

:focus-visible {
  outline: 2px solid rgba(37, 99, 235, 0.48);
  outline-offset: 2px;
}

.hub-app {
  min-height: 100dvh;
  padding: 0 24px 28px;
}

.hub-shell {
  max-width: 1520px;
  margin: 0 auto;
}

.hub-topbar {
  position: sticky;
  top: 0;
  z-index: 40;
  display: grid;
  gap: 14px;
  padding: 18px 0 16px;
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--hub-border);
}

.hub-brand {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px 16px;
}

.hub-brand-line {
  display: inline-flex;
  align-items: center;
}

.hub-mark {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 10px;
  border-radius: 999px;
  background: var(--hub-surface-soft);
  color: var(--hub-muted);
  font-size: 12px;
  font-weight: 700;
}

.hub-mark i {
  color: var(--hub-accent);
}

.hub-title {
  margin: 0;
  font-size: clamp(1.65rem, 2vw, 2.25rem);
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: 0;
}

.hub-subtitle {
  margin: 0;
  color: var(--hub-subtle);
  font-size: 13px;
  line-height: 1.5;
}

.hub-actions {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 14px 18px;
  align-items: center;
}

.hub-search {
  position: relative;
  max-width: 640px;
  width: 100%;
}

.hub-search i {
  position: absolute;
  left: 14px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--hub-subtle);
}

.hub-search input {
  width: 100%;
  min-height: 46px;
  padding: 0 16px 0 40px;
  border-radius: 12px;
  border: 1px solid var(--hub-border);
  background: #ffffff;
  color: var(--hub-text);
}

.hub-search input::placeholder {
  color: var(--hub-subtle);
}

.hub-stats {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: flex-end;
}

.hub-stat {
  min-width: 108px;
  display: grid;
  gap: 4px;
  padding: 9px 12px;
  border: 1px solid var(--hub-border);
  border-radius: 12px;
  background: #ffffff;
}

.hub-stat-label {
  color: var(--hub-subtle);
  font-size: 11px;
  font-weight: 600;
}

.hub-stat-value {
  color: var(--hub-text);
  font-size: 1.3rem;
  font-weight: 800;
  line-height: 1;
}

.hub-layout {
  display: grid;
  grid-template-columns: 260px minmax(0, 1fr);
  gap: 24px;
  align-items: start;
  padding-top: 20px;
}

.hub-rail {
  position: sticky;
  top: 104px;
  align-self: start;
  display: grid;
  gap: 14px;
  padding-right: 20px;
  border-right: 1px solid var(--hub-border);
}

.hub-rail-header {
  display: grid;
  gap: 4px;
}

.hub-rail-title {
  margin: 0;
  font-size: 14px;
  font-weight: 700;
}

.hub-rail-copy {
  margin: 0;
  color: var(--hub-subtle);
  font-size: 12px;
  line-height: 1.5;
}

.hub-chapter-list {
  display: grid;
  gap: 8px;
}

.hub-chapter-btn {
  width: 100%;
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 10px;
  align-items: center;
  padding: 12px 14px;
  border: 1px solid transparent;
  border-radius: 12px;
  background: #ffffff;
  color: var(--hub-muted);
  text-align: left;
  transition: border-color 0.18s ease, background 0.18s ease, color 0.18s ease;
}

.hub-chapter-btn:hover {
  border-color: var(--hub-border);
  background: var(--hub-surface-soft);
}

.hub-chapter-btn.is-active {
  border-color: var(--hub-border-strong);
  background: rgba(37, 99, 235, 0.05);
  color: var(--hub-text);
}

.hub-chapter-name {
  display: grid;
  gap: 3px;
  min-width: 0;
}

.hub-chapter-name strong {
  font-size: 14px;
  line-height: 1.35;
}

.hub-chapter-name span {
  color: var(--hub-subtle);
  font-size: 12px;
  line-height: 1.45;
}

.hub-count {
  min-width: 34px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 4px 8px;
  border-radius: 999px;
  background: var(--hub-surface-soft);
  color: var(--hub-muted);
  font-size: 12px;
  font-weight: 700;
}

.hub-content {
  display: grid;
  gap: 18px;
}

.hub-recent-card,
.hub-panel {
  display: grid;
  gap: 14px;
}

.hub-recent-card {
  display: none;
  padding: 0 0 18px;
  border-bottom: 1px solid var(--hub-border);
}

.hub-recent-card.is-visible {
  display: grid;
}

.hub-panel {
  padding: 0;
}

.hub-panel-header {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 14px;
  align-items: end;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--hub-border);
}

.hub-panel-title {
  margin: 0;
  font-size: 1.2rem;
  font-weight: 700;
  line-height: 1.3;
}

.hub-panel-copy {
  margin: 6px 0 0;
  color: var(--hub-subtle);
  font-size: 13px;
  line-height: 1.55;
}

.hub-filter-note {
  color: var(--hub-subtle);
  font-size: 13px;
  font-weight: 600;
}

.hub-section-stack {
  display: grid;
  gap: 12px;
  padding-top: 16px;
}

.hub-lab-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
  padding-top: 16px;
}

.hub-lab-card {
  display: grid;
  grid-template-columns: 48px minmax(0, 1fr);
  gap: 14px;
  padding: 14px 16px;
  border: 1px solid var(--hub-border);
  border-radius: var(--hub-radius);
  background: #ffffff;
  transition: border-color 0.18s ease, background 0.18s ease, transform 0.18s ease;
}

.hub-lab-card:hover {
  transform: translateY(-1px);
  border-color: var(--hub-border-strong);
  background: #fbfdff;
}

.hub-lab-icon {
  width: 48px;
  height: 48px;
  border-radius: 12px;
  display: grid;
  place-items: center;
  font-size: 16px;
  color: var(--hub-accent-strong);
  background: #eff6ff;
}

.hub-lab-body {
  display: grid;
  gap: 8px;
  min-width: 0;
}

.hub-lab-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.hub-ordinal,
.hub-tag {
  display: inline-flex;
  align-items: center;
  padding: 4px 8px;
  border-radius: 999px;
  font-size: 11px;
  font-weight: 700;
}

.hub-ordinal {
  background: var(--hub-surface-soft);
  color: var(--hub-muted);
}

.hub-tag {
  background: rgba(37, 99, 235, 0.08);
  color: var(--hub-accent-strong);
}

.hub-lab-name {
  margin: 0;
  font-size: 1rem;
  font-weight: 700;
  line-height: 1.45;
}

.hub-lab-foot {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 8px;
  color: var(--hub-accent-strong);
  font-size: 13px;
  font-weight: 700;
}

.hub-empty {
  padding: 18px;
  border: 1px dashed rgba(148, 163, 184, 0.55);
  border-radius: var(--hub-radius);
  color: var(--hub-subtle);
  text-align: center;
  font-size: 14px;
  line-height: 1.7;
}

@media (max-width: 1180px) {
  .hub-actions {
    grid-template-columns: 1fr;
  }

  .hub-stats {
    justify-content: flex-start;
  }

  .hub-layout {
    grid-template-columns: 1fr;
  }

  .hub-rail {
    position: static;
    padding-right: 0;
    padding-bottom: 14px;
    border-right: 0;
    border-bottom: 1px solid var(--hub-border);
  }

  .hub-chapter-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 820px) {
  .hub-app {
    padding: 0 14px 20px;
  }

  .hub-topbar {
    position: static;
    gap: 12px;
    padding: 14px 0 12px;
  }

  .hub-brand {
    display: grid;
    gap: 8px;
  }

  .hub-title {
    font-size: 1.12rem;
  }

  .hub-subtitle {
    display: none;
  }

  .hub-mark {
    padding: 5px 9px;
    font-size: 11px;
  }

  .hub-search {
    max-width: none;
  }

  .hub-search input {
    min-height: 44px;
    border-radius: 10px;
  }

  .hub-stats {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 8px;
    width: 100%;
  }

  .hub-stat {
    min-width: 0;
    padding: 9px 10px;
  }

  .hub-layout {
    gap: 18px;
    padding-top: 16px;
  }

  .hub-chapter-list,
  .hub-lab-grid {
    grid-template-columns: 1fr;
  }

  .hub-panel-header {
    gap: 10px;
  }

  .hub-lab-card {
    padding: 13px 14px;
    border-radius: 12px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation: none !important;
    transition: none !important;
    scroll-behavior: auto !important;
  }
}