/* ========== 页面骨架：顶栏 / 侧栏 / 内容 ========== */
.topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--bg-elev);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(8px);
}

.topbar-inner {
  max-width: 1240px;
  margin: 0 auto;
  padding: 0.6rem 1.2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 700;
  font-size: 1.02rem;
  color: var(--accent);
}
.brand-logo { display: block; }

.topbar-right { display: flex; align-items: center; gap: 0.8rem; }

.progress-pill {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--ink-2);
}
.progress-track {
  width: 110px;
  height: 6px;
  border-radius: 3px;
  background: var(--bg-soft);
  border: 1px solid var(--line);
  overflow: hidden;
}
.progress-fill {
  height: 100%;
  width: 0%;
  background: var(--accent);
  transition: width 0.4s ease;
}

.icon-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  border-radius: var(--radius);
  border: 1px solid var(--line);
  background: var(--bg-elev);
  color: var(--ink-2);
}
.icon-btn:hover { background: var(--bg-soft); color: var(--ink); }

.page {
  max-width: 1240px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 264px minmax(0, 1fr);
  gap: 2rem;
  padding: 1.6rem 1.2rem 4rem;
}

.sidebar {
  position: sticky;
  top: 64px;
  align-self: start;
  max-height: calc(100vh - 80px);
  overflow-y: auto;
  padding-right: 0.4rem;
}

.toc-group { margin-bottom: 0.9rem; }
.toc-group-title {
  font-size: 0.74rem;
  font-weight: 700;
  text-transform: uppercase;
  color: var(--ink-3);
  padding: 0 0.6rem;
  margin-bottom: 0.25rem;
}
.toc-link {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  width: 100%;
  text-align: left;
  border: none;
  background: none;
  color: var(--ink-2);
  font-size: 0.88rem;
  padding: 0.34rem 0.6rem;
  border-radius: 6px;
  line-height: 1.4;
}
.toc-link:hover { background: var(--bg-soft); color: var(--ink); text-decoration: none; }
.toc-link.active {
  background: var(--accent-soft);
  color: var(--accent);
  font-weight: 600;
}
.toc-num {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--ink-3);
  flex: 0 0 1.4em;
}
.toc-link.active .toc-num { color: var(--accent); }
.toc-check {
  margin-left: auto;
  color: var(--ok);
  flex: 0 0 auto;
  display: none;
}
.toc-link.done .toc-check { display: inline; }

.content {
  min-width: 0;
  outline: none;
}

.section-hero {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--bg-elev);
  padding: 1.6rem 1.8rem;
  margin-bottom: 1.4rem;
  box-shadow: var(--shadow);
}
.section-kicker {
  font-family: var(--mono);
  font-size: 0.76rem;
  color: var(--accent);
  font-weight: 600;
  margin-bottom: 0.4rem;
}
.section-hero p.lead {
  font-size: 1.02rem;
  color: var(--ink-2);
  max-width: 62ch;
}
.crumb {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.8rem;
  color: var(--accent);
  background: none;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 0.28rem 0.8rem;
  margin-bottom: 0.9rem;
  cursor: pointer;
}
.crumb:hover { border-color: var(--accent); }

.subpage-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 0.9rem;
  margin: 1.2rem 0;
  max-width: none !important;
}
.subpage-card {
  text-align: left;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--bg-elev);
  padding: 1rem 1.1rem;
  cursor: pointer;
  transition: border-color 0.15s ease, transform 0.15s ease;
}
.subpage-card:hover { border-color: var(--accent); transform: translateY(-2px); }
.subpage-card .sp-num {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--accent);
  font-weight: 600;
}
.subpage-card .sp-title { font-weight: 650; margin: 0.3rem 0 0.35rem; }
.subpage-card .sp-desc { font-size: 0.84rem; color: var(--ink-3); line-height: 1.5; }

.section-body > * { max-width: 78ch; }
.section-body > .full-bleed { max-width: none; }

.section-nav {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 3rem;
  padding-top: 1.2rem;
  border-top: 1px solid var(--line);
}
.section-nav button {
  border: 1px solid var(--line);
  background: var(--bg-elev);
  color: var(--ink-2);
  border-radius: var(--radius);
  padding: 0.55rem 1rem;
  font-size: 0.9rem;
  max-width: 46%;
  text-align: left;
}
.section-nav button:hover { border-color: var(--accent); color: var(--accent); }
.section-nav .next { margin-left: auto; text-align: right; }
.section-nav .nav-label {
  display: block;
  font-size: 0.72rem;
  color: var(--ink-3);
  font-family: var(--mono);
}

.mark-done-row {
  margin-top: 2rem;
  display: flex;
  align-items: center;
  gap: 0.8rem;
}
.mark-done-row .hint { color: var(--ink-3); font-size: 0.85rem; }

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  border-radius: var(--radius);
  border: 1px solid var(--line);
  background: var(--bg-elev);
  color: var(--ink);
  padding: 0.5rem 1rem;
  font-size: 0.9rem;
}
.btn:hover { border-color: var(--accent); }
.btn.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}
.btn.primary:hover { filter: brightness(1.08); }
.btn.done {
  background: var(--ok-soft);
  border-color: var(--ok);
  color: var(--ok);
}

.sidebar-toggle {
  display: none;
  position: fixed;
  left: 14px;
  bottom: 16px;
  z-index: 60;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 1px solid var(--line);
  background: var(--bg-elev);
  color: var(--ink);
  box-shadow: var(--shadow);
}

@media (max-width: 960px) {
  .page { grid-template-columns: 1fr; gap: 0; }
  .sidebar {
    position: fixed;
    inset: 0 auto 0 0;
    top: 0;
    z-index: 70;
    width: 280px;
    max-height: none;
    background: var(--bg-elev);
    border-right: 1px solid var(--line);
    padding: 1rem;
    transform: translateX(-105%);
    transition: transform 0.25s ease;
    box-shadow: var(--shadow);
  }
  .sidebar.open { transform: translateX(0); }
  .sidebar-toggle { display: inline-flex; align-items: center; justify-content: center; }
}