/* =============================================
   路韬的AI学习小站 — 样式
   ============================================= */

:root {
  --accent: #4f46e5;
  --accent-light: #818cf8;
  --accent-bg: #eef2ff;

  --sidebar-bg: #f8f9fb;
  --sidebar-border: #e5e7eb;
  --sidebar-width: 260px;

  --bg: #ffffff;
  --bg-secondary: #f9fafb;
  --text: #111827;
  --text-secondary: #6b7280;
  --text-tertiary: #9ca3af;

  --card-bg: #ffffff;
  --card-border: #e5e7eb;
  --card-shadow: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --card-hover-shadow: 0 4px 12px rgba(0,0,0,0.08);

  --topbar-border: #e5e7eb;
  --menu-hover: #f3f4f6;
  --menu-active-bg: #eef2ff;
  --menu-active-text: #4f46e5;

  --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --radius: 8px;
  --radius-sm: 6px;
  --radius-lg: 12px;
  --transition: 0.2s ease;
}

[data-theme="dark"] {
  --accent: #818cf8;
  --accent-light: #a5b4fc;
  --accent-bg: #1e1b4b;
  --sidebar-bg: #1e1e2e;
  --sidebar-border: #2d2d3d;
  --bg: #13131f;
  --bg-secondary: #1a1a2e;
  --text: #e2e8f0;
  --text-secondary: #94a3b8;
  --text-tertiary: #64748b;
  --card-bg: #1e1e2e;
  --card-border: #2d2d3d;
  --card-shadow: 0 1px 3px rgba(0,0,0,0.2);
  --card-hover-shadow: 0 4px 12px rgba(0,0,0,0.3);
  --topbar-border: #2d2d3d;
  --menu-hover: #2d2d3d;
  --menu-active-bg: #1e1b4b;
  --menu-active-text: #a5b4fc;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 15px; scroll-behavior: smooth; }
body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  display: flex;
  min-height: 100vh;
  overflow-x: hidden;
}
a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent-light); }
button { cursor: pointer; font: inherit; border: none; background: none; color: inherit; }
input { font: inherit; border: none; outline: none; background: transparent; color: inherit; }

.sidebar {
  position: fixed; top: 0; left: 0; bottom: 0;
  width: var(--sidebar-width);
  background: var(--sidebar-bg);
  border-right: 1px solid var(--sidebar-border);
  display: flex; flex-direction: column;
  z-index: 100;
  transition: transform var(--transition), width var(--transition);
}
.sidebar.collapsed { transform: translateX(-100%); }

.main-content {
  flex: 1; margin-left: var(--sidebar-width);
  display: flex; flex-direction: column; min-height: 100vh;
  transition: margin-left var(--transition);
}
.main-content.expanded { margin-left: 0; }

.sidebar-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 18px 16px;
  border-bottom: 1px solid var(--sidebar-border);
}
.logo { display: flex; align-items: center; gap: 10px; }
.logo-icon {
  width: 34px; height: 34px;
  background: var(--accent); border-radius: var(--radius);
  display: flex; align-items: center; justify-content: center;
  color: #fff;
}
.logo-text { font-size: 1.05rem; font-weight: 700; letter-spacing: -0.02em; }

.sidebar-toggle {
  width: 28px; height: 28px;
  display: flex; align-items: center; justify-content: center;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  transition: background var(--transition);
}
.sidebar-toggle:hover { background: var(--menu-hover); color: var(--text); }

.sidebar-nav { flex: 1; min-height: 0; overflow-y: auto; padding: 10px 0; }
.sidebar-nav::-webkit-scrollbar { width: 4px; }
.sidebar-nav::-webkit-scrollbar-thumb { background: var(--text-tertiary); border-radius: 4px; }

.nav-section-title {
  display: flex; align-items: center; gap: 8px;
  padding: 8px 16px;
  font-size: 0.78rem; font-weight: 600; text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-tertiary);
  cursor: pointer; user-select: none;
  transition: color var(--transition);
}
.nav-section-title:hover { color: var(--text-secondary); }
.nav-section-title .chevron { margin-left: auto; transition: transform var(--transition); opacity: 0.5; }
.nav-section-title .chevron.open { transform: rotate(90deg); }

.nav-item {
  display: flex; align-items: center; gap: 10px;
  padding: 8px 16px 8px 28px;
  font-size: 0.88rem;
  color: var(--text-secondary);
  cursor: pointer;
  transition: background var(--transition), color var(--transition);
  position: relative;
}
.nav-item:hover { background: var(--menu-hover); color: var(--text); }
.nav-item.active {
  background: var(--menu-active-bg); color: var(--menu-active-text); font-weight: 500;
}
.nav-item.active::before {
  content: '';
  position: absolute; left: 0; top: 4px; bottom: 4px;
  width: 3px; background: var(--accent); border-radius: 0 3px 3px 0;
}
.nav-item .nav-icon { width: 18px; display: flex; align-items: center; justify-content: center; flex-shrink: 0; }

.nav-children { overflow: hidden; max-height: 0; transition: max-height 0.25s ease; }
.nav-children.open { max-height: 5000px; }
.nav-children .nav-item { padding-left: 48px; font-size: 0.85rem; }
.nav-subsection-title { padding: 6px 0 6px 36px; font-size: 0.73rem; font-weight: 600; color: var(--text-tertiary); text-transform: uppercase; letter-spacing: 0.5px; display: flex; align-items: center; gap: 6px; cursor: pointer; user-select: none; }
.nav-subsection-title:hover { color: var(--text-primary); }
.nav-subsection-title .chevron { margin-left: auto; margin-right: 8px; transition: transform 0.2s ease; }
.nav-subsection-title .chevron.open { transform: rotate(90deg); }
.nav-subsection-children { overflow: hidden; max-height: 0; transition: max-height 0.25s ease; }
.nav-subsection-children.open { max-height: 2000px; }

.topbar {
  display: flex; align-items: center; justify-content: space-between;
  padding: 12px 32px;
  border-bottom: 1px solid var(--topbar-border);
  background: var(--bg);
  position: sticky; top: 0; z-index: 50;
}
.topbar-left { display: flex; align-items: center; gap: 12px; }
.mobile-menu-btn {
  display: none; width: 32px; height: 32px;
  align-items: center; justify-content: center;
  border-radius: var(--radius-sm); color: var(--text-secondary);
}
.mobile-menu-btn:hover { background: var(--menu-hover); }
.breadcrumb { font-size: 0.9rem; color: var(--text-secondary); }
.breadcrumb-current { color: var(--text); font-weight: 500; }
.topbar-right { display: flex; align-items: center; gap: 10px; }

.topbar-clock {
  font-size: 0.82rem; font-weight: 600; color: var(--text-secondary);
  letter-spacing: 0.02em; white-space: nowrap; min-width: 50px; text-align: center;
  user-select: none;
}

.search-box {
  display: flex; align-items: center; gap: 8px;
  background: var(--bg-secondary);
  border: 1px solid var(--card-border);
  border-radius: var(--radius);
  padding: 6px 12px; width: 200px;
  color: var(--text-tertiary);
  transition: border-color var(--transition);
}
.search-box:focus-within { border-color: var(--accent); color: var(--text-secondary); }
.search-box input { font-size: 0.85rem; width: 100%; }
.search-box input::placeholder { color: var(--text-tertiary); }
.search-clear {
  display: none; align-items: center; justify-content: center;
  width: 20px; height: 20px; border-radius: 50%; flex-shrink: 0;
  color: var(--text-tertiary); cursor: pointer; transition: all var(--transition);
}
.search-clear:hover { background: var(--card-border); color: var(--text); }

.topbar-btn {
  position: relative; width: 34px; height: 34px;
  display: flex; align-items: center; justify-content: center;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  transition: background var(--transition), color var(--transition);
}
.topbar-btn:hover { background: var(--menu-hover); color: var(--text); }
.badge {
  position: absolute; top: 4px; right: 4px;
  width: 16px; height: 16px;
  background: #ef4444; color: #fff;
  font-size: 0.6rem; font-weight: 700; border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
}

.content-area {
  flex: 1; padding: 28px 32px 40px;
  max-width: 1200px; width: 100%; margin: 0 auto;
}

/* ======== Welcome & Stats ======== */
.welcome-section {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  padding: 28px 32px;
  margin-bottom: 24px;
  box-shadow: var(--card-shadow);
}
.welcome-row {
  display: flex; align-items: center; justify-content: space-between;
}
.welcome-text h1 {
  font-size: 1.5rem; font-weight: 700; letter-spacing: -0.02em;
  margin-bottom: 6px;
}
.welcome-text p {
  font-size: 0.9rem; color: var(--text-secondary);
}
.welcome-streak {
  background: var(--accent-bg); color: var(--accent);
  padding: 8px 16px; border-radius: 20px;
  font-size: 0.82rem; font-weight: 600; white-space: nowrap;
}
.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
  margin-bottom: 28px;
}
.stat-card {
  display: flex; align-items: center; gap: 12px;
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  padding: 18px;
  box-shadow: var(--card-shadow);
  cursor: pointer;
}
.stat-icon {
  width: 40px; height: 40px; border-radius: var(--radius);
  display: flex; align-items: center; justify-content: center; flex-shrink: 0;
}
.stat-icon.purple { background: #ede9fe; color: #7c3aed; }
.stat-icon.green { background: #d1fae5; color: #059669; }
.stat-icon.blue { background: #dbeafe; color: #2563eb; }
.stat-icon.orange { background: #fff7ed; color: #ea580c; }
[data-theme="dark"] .stat-icon.purple { background: #2d1f4e; color: #a78bfa; }
[data-theme="dark"] .stat-icon.green { background: #064e3b; color: #6ee7b7; }
[data-theme="dark"] .stat-icon.blue { background: #1e3a5f; color: #93c5fd; }
[data-theme="dark"] .stat-icon.orange { background: #431407; color: #fdba74; }
.stat-value {
  font-size: 1.3rem; font-weight: 700; line-height: 1.1;
}
.stat-label {
  font-size: 0.76rem; color: var(--text-secondary);
}

/* ---- Hello 页面：隐藏侧栏 ---- */
body.hello-page .sidebar { display: none; }
body.hello-page .main-content { margin-left: 0; }
body.hello-page .topbar-toggle,
body.hello-page .mobile-menu-btn { display: none; }
body.hello-page .topbar-left { gap: 0; }

/* ---- Hello 页面 Let's begin 按钮 ---- */
.lets-begin-btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 12px 32px;
  font-size: 1rem; font-weight: 600;
  color: #fff;
  background: linear-gradient(135deg, #818cf8, #6366f1);
  border: none; border-radius: 50px;
  cursor: pointer;
  transition: transform var(--transition), box-shadow var(--transition);
}
.lets-begin-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(99,102,241,0.35);
}

.section-header { display: flex; align-items: center; justify-content: space-between; margin-bottom: 16px; }
.section-header h2 { font-size: 1.1rem; font-weight: 600; }
.section-header .see-all { font-size: 0.82rem; color: var(--accent); cursor: pointer; }

/* ======== Knowledge Area Cards ======== */
.area-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
  margin-bottom: 28px;
}
.area-card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--card-shadow);
  display: flex; flex-direction: column;
}
.area-header {
  display: flex; align-items: center; gap: 10px;
  padding: 8px 14px; cursor: pointer;
  border-radius: var(--radius-lg) var(--radius-lg) 0 0;
}
.area-icon {
  width: 24px; height: 24px; border-radius: 6px;
  display: flex; align-items: center; justify-content: center;
  color: #fff; flex-shrink: 0; font-size: 0.7rem;
}
.area-label { font-size: 0.85rem; font-weight: 700; flex: 1; }
.area-count {
  font-size: 0.7rem; padding: 2px 8px; border-radius: 10px;
  font-weight: 600;
}
.area-pills {
  display: flex; flex-wrap: wrap; gap: 5px; padding: 0 16px 14px;
}
.area-pill {
  display: inline-block; padding: 4px 10px;
  border-radius: 6px; font-size: 0.73rem;
  background: var(--bg-secondary); color: var(--text-secondary);
  cursor: pointer; white-space: nowrap;
  border: 1px solid transparent;
  }


/* ======== Progress Cards ======== */
.prog-list { display: flex; flex-direction: column; gap: 14px; }
.prog-card {
  display: flex; align-items: flex-start; gap: 14px;
  background: var(--card-bg); border: 1px solid var(--card-border);
  border-radius: var(--radius-lg); padding: 18px;
  box-shadow: var(--card-shadow); cursor: pointer;
  }
.prog-icon {
  width: 40px; height: 40px; border-radius: 10px;
  display: flex; align-items: center; justify-content: center; flex-shrink: 0;
}
.prog-icon.py { background: #dbeafe; color: #2563eb; }
.prog-icon.ml { background: #ede9fe; color: #7c3aed; }
.prog-icon.llm { background: #e0e7ff; color: #4f46e5; }
.prog-info { flex: 1; min-width: 0; }
.prog-top { display: flex; align-items: center; justify-content: space-between; margin-bottom: 4px; }
.prog-top h4 { font-size: 0.92rem; font-weight: 600; margin: 0; }
.prog-pct { font-size: 0.9rem; font-weight: 700; white-space: nowrap; }
.prog-desc { font-size: 0.78rem; color: var(--text-secondary); margin-bottom: 8px; line-height: 1.4; }
.prog-meta { display: flex; gap: 16px; font-size: 0.73rem; color: var(--text-tertiary); margin-bottom: 10px; }
.prog-bar { height: 5px; background: var(--bg-secondary); border-radius: 3px; overflow: hidden; }
.prog-fill { height: 100%; border-radius: 3px; transition: width 0.6s ease; }

/* ======== Resources ======== */
.res-list { display: flex; flex-direction: column; gap: 6px; }
.res-item {
  display: flex; align-items: center; gap: 10px;
  padding: 10px 14px; border-radius: 10px;
  background: var(--bg-secondary); border: 1px solid transparent;
  cursor: pointer; }

.res-dot { width: 7px; height: 7px; border-radius: 50%; flex-shrink: 0; }
.res-dot.yt { background: #ef4444; }
.res-dot.doc { background: #3b82f6; }
.res-dot.git { background: #7c3aed; }
.res-dot.blog { background: #10b981; }
.res-text { flex: 1; display: flex; align-items: center; justify-content: space-between; gap: 8px; }
.res-title { font-size: 0.84rem; color: var(--text); }
.res-tag { font-size: 0.68rem; padding: 2px 8px; border-radius: 10px; background: var(--accent-bg); color: var(--accent); white-space: nowrap; }

/* ======== Timeline ======== */
.timeline { position: relative; padding-left: 30px; }
.timeline::before {
  content: ''; position: absolute; left: 12px; top: 6px; bottom: 6px;
  width: 2px; background: var(--card-border); border-radius: 1px;
}
.tl-item {
  position: relative; padding: 11px 0 11px 16px; cursor: pointer;
}
.tl-item:last-child { padding-bottom: 0; }
.tl-dot {
  position: absolute; left: -30px; top: 10px;
  width: 26px; height: 26px; border-radius: 50%;
  background: var(--card-bg); border: 2px solid var(--card-border);
  display: flex; align-items: center; justify-content: center;
  font-size: 0.7rem; font-weight: 700; color: var(--text-tertiary);
  z-index: 1; }
.tl-item.done .tl-dot { background: #10b981; border-color: #10b981; color: #fff; }
.tl-item.current .tl-dot {
  background: var(--accent); border-color: var(--accent); color: #fff;
  box-shadow: 0 0 0 4px rgba(79,70,229,0.15);
}
.tl-content h4 { font-size: 0.88rem; font-weight: 600; margin-bottom: 2px; }
.tl-content p { font-size: 0.78rem; color: var(--text-secondary); line-height: 1.3; }
.tl-item.done .tl-content h4 { color: var(--text-secondary); }
.tl-item.current .tl-content h4 { color: var(--accent); }

/* ======== Two-column layout ======== */
.dash-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; margin-bottom: 4px; }

.section-header { display: flex; align-items: center; justify-content: space-between; margin-bottom: 16px; }
.section-header h2 { font-size: 1.1rem; font-weight: 600; }
.section-header .see-all { font-size: 0.82rem; color: var(--accent); cursor: pointer; }

.course-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; margin-bottom: 32px; }
.course-card {
  background: var(--card-bg); border: 1px solid var(--card-border);
  border-radius: var(--radius-lg); padding: 20px;
  box-shadow: var(--card-shadow); cursor: pointer;
  transition: box-shadow var(--transition), transform var(--transition);
}
.course-card:hover { box-shadow: var(--card-hover-shadow); transform: translateY(-2px); }
.course-card .course-icon { width: 40px; height: 40px; border-radius: var(--radius); display: flex; align-items: center; justify-content: center; margin-bottom: 12px; font-size: 1.2rem; }
.course-card .course-icon.py { background: #dbeafe; color: #2563eb; }
.course-card .course-icon.ml { background: #fae8ff; color: #a855f7; }
.course-card .course-icon.dl { background: #fce7f3; color: #ec4899; }
.course-card .course-icon.nlp { background: #d1fae5; color: #059669; }
.course-card .course-icon.cv { background: #fef3c7; color: #d97706; }
.course-card .course-icon.llm { background: #e0e7ff; color: #4f46e5; }
.course-card h3 { font-size: 0.95rem; font-weight: 600; margin-bottom: 4px; }
.course-card .course-desc { font-size: 0.82rem; color: var(--text-secondary); margin-bottom: 12px; line-height: 1.4; }
.course-card .course-meta { display: flex; align-items: center; gap: 12px; font-size: 0.78rem; color: var(--text-tertiary); }
.course-card .course-meta span { display: flex; align-items: center; gap: 4px; }
.course-card .course-progress { margin-top: 12px; height: 4px; background: var(--bg-secondary); border-radius: 2px; overflow: hidden; }
.course-card .course-progress .fill { height: 100%; background: var(--accent); border-radius: 2px; }

.path-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 12px; margin-bottom: 32px; }
.path-card {
  background: var(--card-bg); border: 1px solid var(--card-border);
  border-radius: var(--radius); padding: 16px;
  display: flex; align-items: center; gap: 12px; cursor: pointer;
  transition: box-shadow var(--transition), transform var(--transition);
}
.path-card:hover { box-shadow: var(--card-hover-shadow); transform: translateY(-1px); }
.path-card .step-badge { width: 28px; height: 28px; border-radius: 50%; background: var(--accent-bg); color: var(--accent); display: flex; align-items: center; justify-content: center; font-size: 0.78rem; font-weight: 700; flex-shrink: 0; }
.path-card .step-badge.done { background: #10b981; color: #fff; }
.path-card .step-content h4 { font-size: 0.88rem; font-weight: 600; margin-bottom: 2px; }
.path-card .step-content p { font-size: 0.78rem; color: var(--text-secondary); }

.resources-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; margin-bottom: 20px; }
.resource-card {
  background: var(--card-bg); border: 1px solid var(--card-border);
  border-radius: var(--radius); padding: 16px;
  display: flex; align-items: flex-start; gap: 12px; cursor: pointer;
  transition: box-shadow var(--transition);
}
.resource-card:hover { box-shadow: var(--card-hover-shadow); }
.resource-card .resource-icon { width: 36px; height: 36px; border-radius: var(--radius-sm); display: flex; align-items: center; justify-content: center; flex-shrink: 0; font-size: 1rem; }
.resource-card .resource-icon.yt { background: #fee2e2; color: #dc2626; }
.resource-card .resource-icon.doc { background: #dbeafe; color: #2563eb; }
.resource-card .resource-icon.git { background: #f3e8ff; color: #7c3aed; }
.resource-card .resource-icon.blog { background: #d1fae5; color: #059669; }
.resource-card .resource-icon.pdf { background: #fef3c7; color: #d97706; }
.resource-card .resource-icon.news { background: #e0e7ff; color: #4f46e5; }
.resource-card .resource-info h4 { font-size: 0.88rem; font-weight: 600; margin-bottom: 2px; }
.resource-card .resource-info p { font-size: 0.78rem; color: var(--text-secondary); line-height: 1.3; }
.resource-card .resource-tag { display: inline-block; margin-top: 4px; padding: 1px 8px; border-radius: 10px; font-size: 0.68rem; font-weight: 500; background: var(--accent-bg); color: var(--accent); }

.sidebar-overlay { display: none; position: fixed; inset: 0; background: rgba(0,0,0,0.4); z-index: 90; opacity: 0; pointer-events: none; transition: opacity var(--transition); }
.sidebar-overlay.show { opacity: 1; pointer-events: auto; }

@media (max-width: 1024px) {
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
  .area-grid { grid-template-columns: repeat(2, 1fr); }
  .dash-grid { grid-template-columns: 1fr; }
  .course-grid { grid-template-columns: repeat(2, 1fr); }
  .resources-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
  .sidebar { transform: translateX(-100%); box-shadow: 4px 0 24px rgba(0,0,0,0.15); }
  .sidebar.mobile-open { transform: translateX(0); }
  .sidebar-overlay.show { display: block; }
  .main-content { margin-left: 0; }
  .mobile-menu-btn { display: flex; }
  .topbar { padding: 10px 16px; }
  .content-area { padding: 20px 16px 32px; }
  .welcome-row { flex-direction: column; align-items: flex-start; gap: 12px; }
  .welcome-streak { align-self: flex-start; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); gap: 10px; }
  .area-grid { grid-template-columns: 1fr; }
  .dash-grid { grid-template-columns: 1fr; }
  .course-grid { grid-template-columns: 1fr; }
  .path-grid { grid-template-columns: 1fr; }
  .resources-grid { grid-template-columns: 1fr; }
  .search-box { width: 140px; }
  .stat-card { padding: 14px; }
  .stat-card .stat-value { font-size: 1.2rem; }
}

@media (max-width: 480px) {
  .stats-grid { grid-template-columns: 1fr 1fr; gap: 8px; }
  .stat-card { padding: 12px; gap: 10px; }
  .stat-card .stat-icon { width: 32px; height: 32px; }
  .stat-card .stat-value { font-size: 1.2rem; }
  .quick-links { gap: 6px; }
  .quick-link { padding: 6px 10px; font-size: 0.76rem; }
  .search-box { width: 110px; }
}

/* =============================================
   内容页面样式
   ============================================= */

.learn-page {
  max-width: 900px;
  margin: 0 auto;
}

.learn-page .page-header {
  margin-bottom: 32px;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--card-border);
}

.learn-page .page-header h1 {
  font-size: 1.6rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 6px;
}

.learn-page .page-header p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  line-height: 1.5;
}

.learn-page .page-progress {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 14px;
  padding: 10px 14px;
  background: var(--bg-secondary);
  border-radius: var(--radius);
  border: 1px solid var(--card-border);
}

.learn-page .page-progress .label {
  font-size: 0.78rem;
  color: var(--text-secondary);
  white-space: nowrap;
}

.learn-page .page-progress .bar {
  flex: 1;
  height: 5px;
  background: var(--card-border);
  border-radius: 3px;
  overflow: hidden;
}

.learn-page .page-progress .bar .fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent), var(--accent-light));
  border-radius: 3px;
  transition: width 0.5s ease;
}

.learn-page .page-progress .pct {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent);
  min-width: 32px;
  text-align: right;
}

/* ---- 目录 ---- */
.learn-toc {
  margin-bottom: 28px;
  padding: 16px 20px;
  background: var(--bg-secondary);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
}

.learn-toc .toc-title {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 10px;
  display: flex;
  align-items: center;
  gap: 6px;
}

.learn-toc .toc-list {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 0;
}

.learn-toc .toc-item {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 4px 12px;
  font-size: 0.82rem;
  color: var(--text-secondary);
  cursor: pointer;
  border-radius: var(--radius-sm);
  transition: background var(--transition), color var(--transition);
  width: 50%;
}

.learn-toc .toc-item:hover {
  background: var(--menu-hover);
  color: var(--accent);
}

.learn-toc .toc-item .num {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--accent-bg);
  color: var(--accent);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.68rem;
  font-weight: 700;
  flex-shrink: 0;
}

.learn-toc .toc-item .num.done {
  background: #10b981;
  color: #fff;
}

/* ---- 内容段落 ---- */
.learn-section {
  margin-bottom: 36px;
  scroll-margin-top: 70px;
}

.learn-section h2 {
  font-size: 1.15rem;
  font-weight: 600;
  margin-bottom: 10px;
  padding-bottom: 6px;
  border-bottom: 2px solid var(--accent-bg);
}

.learn-section h3 {
  font-size: 0.98rem;
  font-weight: 600;
  margin: 16px 0 8px;
  color: var(--text);
}

.learn-section p {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 10px;
}

.learn-section ul, .learn-section ol {
  padding-left: 20px;
  margin-bottom: 10px;
}

.learn-section li {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 4px;
}

.learn-section strong {
  color: var(--text);
  font-weight: 600;
}

/* ---- 代码块 ---- */
.learn-section pre {
  margin: 10px 0 14px;
  border-radius: var(--radius);
  border: 1px solid var(--card-border);
  overflow: hidden;
  position: relative;
  background: var(--bg-secondary) !important;
}

.learn-section pre code {
  font-size: 0.82rem;
  line-height: 1.6;
  padding: 14px 16px !important;
  background: transparent !important;
  color: #2563eb !important;
}

.learn-section pre:has(.copy-btn:hover) {
  border-color: var(--accent);
  box-shadow: 0 0 0 1px var(--accent);
}

.copy-btn {
  position: absolute;
  top: 6px;
  right: 6px;
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  color: var(--text-tertiary);
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  opacity: 0;
  transition: opacity var(--transition);
  z-index: 2;
}

pre:hover .copy-btn {
  opacity: 1;
}

.copy-btn:hover {
  color: var(--accent);
  border-color: var(--accent);
}

.copy-btn.copied {
  color: #10b981;
  border-color: #10b981;
}

/* ---- 信息/提示/警告框 ---- */
.info-box {
  padding: 12px 16px;
  border-radius: var(--radius);
  border-left: 3px solid var(--accent);
  background: var(--accent-bg);
  margin: 12px 0;
}

.info-box p {
  font-size: 0.82rem;
  color: var(--accent);
  margin-bottom: 0 !important;
}

.info-box.tip {
  border-left-color: #10b981;
  background: #ecfdf5;
}

.info-box.tip p { color: #047857; }

.info-box.warn {
  border-left-color: #f59e0b;
  background: #fffbeb;
}

.info-box.warn p { color: #b45309; }

[data-theme="dark"] .info-box.tip { background: #064e3b; }
[data-theme="dark"] .info-box.tip p { color: #6ee7b7; }
[data-theme="dark"] .info-box.warn { background: #451a03; }
[data-theme="dark"] .info-box.warn p { color: #fbbf24; }

/* ---- 练习框 ---- */
.exercise-box {
  padding: 16px 20px;
  border-radius: var(--radius-lg);
  border: 2px solid var(--card-border);
  background: var(--bg-secondary);
  margin: 16px 0;
}

.exercise-box .ex-title {
  font-size: 0.88rem;
  font-weight: 600;
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 6px;
}

.exercise-box p {
  font-size: 0.85rem;
  margin-bottom: 8px !important;
}

.exercise-box .hint-btn {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: 0.8rem;
  color: var(--accent);
  cursor: pointer;
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--accent);
  background: transparent;
  transition: background var(--transition);
  margin-top: 4px;
}

.exercise-box .hint-btn:hover {
  background: var(--accent-bg);
}

.exercise-box .hint-content {
  display: none;
  margin-top: 8px;
  padding: 10px;
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-sm);
  font-size: 0.82rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.exercise-box .hint-content.show {
  display: block;
}

/* ---- 完成标记 ---- */
.section-check {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.78rem;
  color: var(--text-tertiary);
  cursor: pointer;
  padding: 3px 8px;
  border-radius: var(--radius-sm);
  transition: background var(--transition), color var(--transition);
  margin-left: 8px;
}

.section-check:hover {
  background: var(--menu-hover);
  color: var(--text-secondary);
}

.section-check.done {
  color: #10b981;
}

/* ---- 表格 ---- */
.learn-section table {
  width: 100%;
  border-collapse: collapse;
  margin: 12px 0;
  font-size: 0.85rem;
}

.learn-section th, .learn-section td {
  padding: 8px 12px;
  border: 1px solid var(--card-border);
  text-align: left;
}

.learn-section th {
  background: var(--bg-secondary);
  font-weight: 600;
  color: var(--text);
}

.learn-section td {
  color: var(--text-secondary);
}

/* ---- 行内代码 ---- */
.learn-section p code,
.learn-section li code,
.learn-section td code {
  font-family: 'JetBrains Mono', 'Fira Code', monospace;
  font-size: 0.82em;
  padding: 1px 5px;
  border-radius: 3px;
  background: var(--bg-secondary);
  border: 1px solid var(--card-border);
  color: var(--accent);
}

/* ---- hljs 深色主题覆盖 ---- */
[data-theme="dark"] .learn-section pre { background: #1e1e2e !important; }
[data-theme="dark"] .learn-section pre code { color: #60a5fa !important; }

/* ---- 练习答案 ---- */
.exercise-box .answer-toggle {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: 0.8rem;
  color: var(--text-tertiary);
  cursor: pointer;
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--card-border);
  background: transparent;
  transition: background var(--transition), color var(--transition);
  margin-top: 4px;
  margin-left: 6px;
}

.exercise-box .answer-toggle:hover {
  background: var(--menu-hover);
  color: var(--text);
}

.exercise-box .answer-content {
  display: none;
  margin-top: 8px;
  padding: 10px;
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-sm);
}

.exercise-box .answer-content.show { display: block; }
.exercise-box .answer-content pre { margin: 6px 0; }

/* ---- Search Results Dropdown ---- */
.search-wrap { position: relative; }
.search-results { position: absolute; top: calc(100% + 4px); left: 0; right: 0; background: var(--card-bg); border: 1px solid var(--card-border); border-radius: var(--radius); box-shadow: 0 8px 24px rgba(0,0,0,0.12); max-height: 300px; overflow-y: auto; display: none; z-index: 200; }
.search-results.show { display: block; }
.search-results .sr-item { display: flex; align-items: center; gap: 8px; padding: 8px 12px; font-size: 0.82rem; color: var(--text-secondary); cursor: pointer; transition: background var(--transition); }
.search-results .sr-item:hover,
.search-results .sr-item.active { background: var(--menu-active-bg); color: var(--accent); }
.search-results .sr-item .sr-icon { width: 24px; height: 24px; border-radius: 4px; background: var(--accent-bg); color: var(--accent); display: flex; align-items: center; justify-content: center; flex-shrink: 0; font-size: 0.7rem; }
.search-results .sr-item .sr-label { flex: 1; min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.search-results .sr-item .sr-label mark { background: #fef08a; color: #854d0e; border-radius: 2px; padding: 0 1px; }
[data-theme="dark"] .search-results .sr-item .sr-label mark { background: #713f12; color: #fef08a; }
.search-results .sr-item .sr-section { font-size: 0.7rem; color: var(--text-tertiary); margin-left: auto; flex-shrink: 0; }
.search-results .sr-empty { padding: 16px 12px; text-align: center; font-size: 0.82rem; color: var(--text-tertiary); display: flex; align-items: center; justify-content: center; gap: 6px; }
@media (max-width: 768px) { .search-results { position: fixed; left: 16px; right: 16px; top: 56px; max-height: 50vh; box-shadow: 0 12px 32px rgba(0,0,0,0.2); } }

/* ---- Mobile Improvements ---- */
@media (max-width: 768px) { .content-area { padding-top: 12px; } .topbar { padding: 8px 12px; } .topbar .search-box { width: 36px; cursor: pointer; } .topbar .search-box input { display: none; } .topbar .search-box.expand { width: calc(100vw - 110px); } .topbar .search-box.expand input { display: block; } }
@media (max-width: 480px) { .stat-value { font-size: 1rem; } .stat-card { padding: 10px; } .stat-card .stat-icon { width: 28px; height: 28px; } .section-header h2 { font-size: 0.95rem; } }
.course-card { cursor: pointer; }

/* ---- Topbar Sidebar Toggle ---- */
.topbar-toggle {
  width: 32px; height: 32px;
  display: flex; align-items: center; justify-content: center;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  transition: background var(--transition), color var(--transition);
  flex-shrink: 0;
}
.topbar-toggle:hover { background: var(--menu-hover); color: var(--text); }
.sidebar-header .sidebar-toggle { display: none; }

/* ---- LLM Engineering Tabbed Page ---- */
.llm-eng-page { max-width: 1000px; }

.llm-eng-tabs {
  display: flex;
  gap: 4px;
  margin-bottom: 24px;
  padding: 4px;
  background: var(--bg-secondary);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  overflow-x: auto;
}

.llm-eng-tab {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 10px 18px;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-secondary);
  border-radius: var(--radius);
  cursor: pointer;
  white-space: nowrap;
  transition: all var(--transition);
  user-select: none;
}

.llm-eng-tab:hover {
  background: var(--menu-hover);
  color: var(--text);
}

.llm-eng-tab.active {
  background: var(--accent);
  color: #fff;
  box-shadow: 0 2px 8px rgba(79,70,229,0.25);
}

.llm-eng-panel { display: none; }
.llm-eng-panel.active { display: block; }

/* ---- 通用板块选项卡（自动生成） ---- */
.section-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  margin-bottom: 24px;
  padding: 4px;
  background: var(--bg-secondary);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
}

.section-tab {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 9px 16px;
  font-size: 0.84rem;
  font-weight: 500;
  color: var(--text-secondary);
  border-radius: var(--radius);
  cursor: pointer;
  white-space: nowrap;
  transition: all var(--transition);
  user-select: none;
}
.section-tab:hover {
  background: var(--menu-hover);
  color: var(--text);
}
.section-tab.active {
  background: var(--accent);
  color: #fff;
  box-shadow: 0 2px 8px rgba(79,70,229,0.25);
}

.section-tab-content { /* wrapper for the actual page content */ }

/* ---- Notification panel ---- */
.notify-panel {
  display: none;
  position: fixed;
  top: 52px;
  right: 60px;
  width: 340px;
  max-height: 420px;
  overflow-y: auto;
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  box-shadow: 0 8px 32px rgba(0,0,0,0.15);
  z-index: 200;
}
.notify-panel.show { display: block; }

.notify-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 14px 16px;
  border-bottom: 1px solid var(--card-border);
  font-weight: 600; font-size: 0.92rem;
}
.notify-clear {
  font-size: 0.76rem; color: var(--text-tertiary);
}
.notify-clear:hover { color: var(--accent); }

.notify-item {
  display: flex; align-items: flex-start; gap: 10px;
  padding: 12px 16px;
  border-bottom: 1px solid var(--card-border);
  transition: background var(--transition);
}
.notify-item:hover { background: var(--bg-secondary); }
.notify-clickable { cursor: pointer; }
.notify-clickable:hover .notify-body p { color: var(--accent); }
.notify-icon {
  flex-shrink: 0;
  width: 32px; height: 32px;
  display: flex; align-items: center; justify-content: center;
  border-radius: 8px;
  background: var(--accent-bg); color: var(--accent);
}
.notify-body { flex: 1; min-width: 0; }
.notify-body p {
  font-size: 0.84rem; line-height: 1.4; color: var(--text);
  margin-bottom: 2px;
}
.notify-time {
  font-size: 0.7rem; color: var(--text-tertiary);
}
.notify-dismiss {
  flex-shrink: 0;
  width: 24px; height: 24px;
  display: flex; align-items: center; justify-content: center;
  border-radius: 4px; color: var(--text-tertiary);
  opacity: 0;
  transition: opacity var(--transition);
}
.notify-item:hover .notify-dismiss { opacity: 1; }
.notify-dismiss:hover { background: var(--menu-hover); color: var(--text); }

.notify-empty {
  display: flex; flex-direction: column; align-items: center; gap: 8px;
  padding: 32px 16px; color: var(--text-tertiary);
}
.notify-empty p { font-size: 0.84rem; }

@media (max-width: 768px) {
  .section-tab {
    padding: 7px 12px;
    font-size: 0.78rem;
    gap: 4px;
  }
}

.llm-eng-panel .page-header {
  margin-bottom: 24px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--card-border);
}

.llm-eng-panel .page-header h1 {
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 6px;
}

.llm-eng-panel .page-header p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  line-height: 1.6;
}

/* ---- Footer ---- */
.site-footer {
  text-align: center;
  padding: 16px 32px 20px;
  border-top: 1px solid var(--card-border);
}

.site-footer a {
  font-size: 0.78rem;
  color: var(--text-tertiary);
  text-decoration: none;
  transition: color var(--transition);
}

.site-footer a:hover {
  color: var(--text-secondary);
}

@media (max-width: 768px) {
  .llm-eng-tabs {
    gap: 2px;
    padding: 3px;
  }

  .llm-eng-tab {
    padding: 8px 12px;
    font-size: 0.78rem;
    gap: 4px;
  }
}