/* ============================================
   跟阿铭学大模型技术 - 企业官网样式
   科技蓝 + 专业教育风格
   ============================================ */

:root {
  --primary: #1a2332;
  --primary-light: #2a3a52;
  --accent: #2563eb;
  --accent-light: #3b82f6;
  --accent-dark: #1d4ed8;
  --gradient: linear-gradient(135deg, #1a2332 0%, #2563eb 100%);
  --gradient-accent: linear-gradient(135deg, #2563eb, #3b82f6);
  --text: #1f2937;
  --text-light: #6b7280;
  --bg: #f8fafc;
  --bg-card: #ffffff;
  --border: #e2e8f0;
  --success: #10b981;
  --warning: #f59e0b;
  --danger: #ef4444;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.12);
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --nav-height: 72px;
  --content-max: 1200px;
}

/* ===== Reset & Base ===== */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--nav-height);
}
body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC',
               'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}
a {
  color: var(--accent);
  text-decoration: none;
  transition: var(--transition);
}
a:hover {
  color: var(--accent-dark);
}
img {
  max-width: 100%;
}

.container {
  max-width: var(--content-max);
  margin: 0 auto;
  padding: 0 24px;
}

/* ===== Navigation ===== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: rgba(255, 255, 255, 0.97);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  z-index: 1000;
  transition: var(--transition);
}
.navbar.scrolled {
  box-shadow: 0 4px 20px rgba(0,0,0,0.08);
}
.navbar .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}
.navbar-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 1.2rem;
  color: var(--primary) !important;
}
.navbar-brand .brand-icon {
  width: 36px;
  height: 36px;
  background: var(--gradient-accent);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-size: 1.2rem;
  font-weight: 800;
}
.nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
  list-style: none;
}
.nav-links a {
  display: block;
  padding: 8px 18px;
  border-radius: 8px;
  color: var(--text);
  font-weight: 500;
  font-size: 0.95rem;
  transition: var(--transition);
}
.nav-links a:hover,
.nav-links a.active {
  background: rgba(37, 99, 235, 0.08);
  color: var(--accent);
}
.nav-cta {
  background: var(--gradient-accent) !important;
  color: #fff !important;
  padding: 8px 24px !important;
  border-radius: 8px !important;
  font-weight: 600 !important;
}
.nav-cta:hover {
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.4) !important;
  transform: translateY(-1px);
}
.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  color: var(--text);
  -webkit-tap-highlight-color: transparent;
}
.nav-toggle:focus,
.nav-toggle:active {
  outline: none;
  background: transparent;
  box-shadow: none;
}
.nav-toggle:focus-visible {
  outline: 2px solid rgba(37, 99, 235, 0.45);
  outline-offset: 2px;
  border-radius: 8px;
}

/* Mobile Nav */
@media (max-width: 768px) {
  .navbar {
    height: auto;
  }
  .nav-toggle {
    display: none;
  }
  .navbar .container {
    flex-wrap: wrap;
    row-gap: 4px;
    height: auto;
    padding-top: 6px;
    padding-bottom: 6px;
  }
  .navbar-brand {
    display: none;
  }
  .nav-links {
    position: static;
    width: 100%;
    flex-wrap: wrap;
    justify-content: center;
    gap: 4px 6px;
    background: transparent;
    padding: 0;
    border: 0;
    box-shadow: none;
    transform: none;
    opacity: 1;
    pointer-events: all;
  }
  .nav-links a {
    width: auto;
    padding: 6px 10px;
    font-size: 0.88rem;
    line-height: 1.2;
    color: var(--accent);
    -webkit-tap-highlight-color: transparent;
  }
  .nav-links a:hover,
  .nav-links a.active {
    background: transparent;
    color: var(--accent);
  }
  .nav-links a:focus,
  .nav-links a:active {
    outline: none;
    background: transparent;
    box-shadow: none;
  }
  .nav-links .nav-cta {
    background: transparent !important;
    color: var(--accent) !important;
    padding: 6px 10px !important;
    border-radius: 8px !important;
    font-weight: 500 !important;
  }
  .nav-links li:nth-child(2),
  .nav-links li:nth-child(3) {
    display: none;
  }
}

/* ===== Hero Section ===== */
.hero {
  padding: calc(var(--nav-height) + 80px) 0 80px;
  background: var(--gradient);
  color: #fff;
  text-align: center;
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle, rgba(255,255,255,0.05) 0%, transparent 60%);
  animation: heroGlow 20s ease-in-out infinite;
}
@keyframes heroGlow {
  0%, 100% { transform: translate(0, 0); }
  50% { transform: translate(5%, 5%); }
}
.hero-content {
  position: relative;
  max-width: 800px;
  margin: 0 auto;
}
.hero h1 {
  font-size: 3rem;
  font-weight: 800;
  margin-bottom: 20px;
  letter-spacing: -0.02em;
  line-height: 1.2;
}
.hero h1 span {
  background: linear-gradient(135deg, #60a5fa, #a78bfa);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero p {
  font-size: 1.2rem;
  color: rgba(255,255,255,0.8);
  margin-bottom: 32px;
  max-width: 650px;
  margin-left: auto;
  margin-right: auto;
}
.hero-intro {
  font-size: 1.1rem;
  line-height: 1.95;
  max-width: 700px;
  color: rgba(255, 255, 255, 0.9);
  letter-spacing: 0.01em;
}
.hero-actions {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 32px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 1rem;
  border: none;
  cursor: pointer;
  transition: var(--transition);
  text-decoration: none;
}
.btn-primary {
  background: #fff;
  color: var(--accent) !important;
}
.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0,0,0,0.2);
}
.btn-outline {
  background: transparent;
  color: #fff !important;
  border: 2px solid rgba(255,255,255,0.3);
}
.btn-outline:hover {
  border-color: #fff;
  background: rgba(255,255,255,0.1);
  transform: translateY(-2px);
}
.hero-meta {
  margin-top: 40px;
  display: flex;
  justify-content: center;
  gap: 48px;
  flex-wrap: wrap;
}
.hero-meta-item {
  text-align: center;
}
.hero-meta-item .num {
  display: block;
  font-size: 1.8rem;
  font-weight: 800;
}
.hero-meta-item .label {
  font-size: 0.9rem;
  color: rgba(255,255,255,0.6);
}

/* ===== Section Common ===== */
.section {
  padding: 80px 0;
}
.section-title {
  text-align: center;
  margin-bottom: 48px;
}
.section-title h2 {
  font-size: 2rem;
  font-weight: 800;
  color: var(--primary);
  margin-bottom: 12px;
  position: relative;
  display: inline-block;
}
.section-title h2::after {
  content: '';
  display: block;
  width: 60px;
  height: 4px;
  background: var(--gradient-accent);
  border-radius: 2px;
  margin: 12px auto 0;
}
.section-title p {
  color: var(--accent);
  font-size: 1rem;
  max-width: 600px;
  margin: 0 auto;
}
.section-alt {
  background: #fff;
}

/* ===== Keywords / Tags ===== */
.keywords-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: center;
  margin-top: 24px;
}
.keyword-tag {
  padding: 8px 20px;
  background: linear-gradient(135deg, #eff6ff, #dbeafe);
  color: var(--accent);
  border-radius: 50px;
  font-size: 0.9rem;
  font-weight: 500;
  transition: var(--transition);
  border: 1px solid rgba(37, 99, 235, 0.15);
}
.keyword-tag:hover {
  background: var(--gradient-accent);
  color: #fff;
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
}

/* ===== Cards Grid ===== */
.grid-2, .grid-3 {
  display: grid;
  gap: 24px;
}
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }

@media (max-width: 768px) {
  .grid-2, .grid-3 {
    grid-template-columns: 1fr;
  }
  .hero {
    padding: calc(var(--nav-height) + 40px) 0 48px;
  }
  .hero h1 { font-size: 1.6rem; }
  .hero p { font-size: 1rem; }
  .hero-meta { gap: 24px; }
  .hero-meta-item .num { font-size: 1.4rem; }
  .btn {
    padding: 12px 24px;
    font-size: 0.9rem;
  }
  .section { padding: 40px 0; }
  .section-title h2 { font-size: 1.5rem; }
  .section-title { margin-bottom: 32px; }
  .card { padding: 24px; }
  .container { padding: 0 16px; }
  .about-content h2 { font-size: 1.25rem; }
  .keyword-tag { padding: 6px 14px; font-size: 0.8rem; }
  .hero-actions { flex-direction: column; align-items: center; }
  .hero-actions .btn { width: 100%; max-width: 280px; justify-content: center; }
  .keywords-cloud { gap: 8px; }
}

.card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 32px;
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
  transition: var(--transition);
}
.card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
}
.card-icon {
  width: 52px;
  height: 52px;
  border-radius: 12px;
  background: linear-gradient(135deg, #eff6ff, #dbeafe);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 16px;
  font-size: 1.5rem;
  color: var(--accent);
}
.card h3 {
  font-size: 1.15rem;
  margin-bottom: 8px;
  color: var(--primary);
}
.card p {
  color: var(--text-light);
  font-size: 0.95rem;
}
#gains .card-icon {
  margin-left: auto;
  margin-right: auto;
}
#gains .card h3 {
  text-align: center;
}

/* ===== Course Format ===== */
.format-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}
@media (max-width: 768px) {
  .format-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}
.format-item {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 24px;
  text-align: center;
  border: 1px solid var(--border);
  transition: var(--transition);
}
.format-item:hover {
  border-color: var(--accent);
  box-shadow: var(--shadow);
}
.format-item .emoji {
  font-size: 2rem;
  margin-bottom: 8px;
  display: block;
}
.format-item .title {
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 4px;
}
.format-item .desc {
  font-size: 0.85rem;
  color: var(--text-light);
}

/* ===== Chapter / Curriculum ===== */
.chapter {
  background: var(--bg-card);
  border-radius: var(--radius);
  margin-bottom: 16px;
  border: 1px solid var(--border);
  overflow: hidden;
  transition: var(--transition);
}
.chapter:hover {
  box-shadow: var(--shadow);
}
.chapter-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 24px;
  cursor: pointer;
  user-select: none;
  transition: var(--transition);
}
.chapter-header:hover {
  background: rgba(37, 99, 235, 0.03);
}
.chapter-header .title {
  font-weight: 700;
  font-size: 1.05rem;
  color: var(--primary);
  display: flex;
  align-items: center;
  gap: 12px;
}
.chapter-header .badge {
  font-size: 0.75rem;
  padding: 2px 10px;
  border-radius: 50px;
  background: rgba(37, 99, 235, 0.1);
  color: var(--accent);
  font-weight: 600;
}
.chapter-header .badge.hot {
  background: rgba(239, 68, 68, 0.1);
  color: var(--danger);
}
.chapter-header .toggle-icon {
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: var(--bg);
  transition: var(--transition);
  font-size: 0.8rem;
  color: var(--text-light);
}
.chapter.open .chapter-header .toggle-icon {
  transform: rotate(180deg);
  background: var(--accent);
  color: #fff;
}
.chapter-body {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease, padding 0.4s ease;
  padding: 0 24px;
}
.chapter.open .chapter-body {
  max-height: none;
  padding: 0 24px 20px;
}
.chapter-body ul {
  list-style: none;
  padding: 0;
}
.chapter-body li {
  padding: 8px 0 8px 28px;
  position: relative;
  color: var(--text);
  border-bottom: 1px solid var(--bg);
  font-size: 0.95rem;
}
.chapter-body li:last-child {
  border-bottom: none;
}
.chapter-body li::before {
  content: '▸';
  position: absolute;
  left: 8px;
  color: var(--accent);
  font-weight: bold;
}
.chapter-body li.level-1 {
  font-weight: 600;
}
.chapter-body li.level-2 {
  padding-left: 46px;
  font-size: 0.92rem;
  color: #334155;
}
.chapter-body li.level-2::before {
  left: 24px;
  content: '•';
  color: #60a5fa;
}
.chapter-body li.level-3,
.chapter-body li.level-4 {
  padding-left: 64px;
  font-size: 0.89rem;
  color: #64748b;
}
.chapter-body li.level-3::before,
.chapter-body li.level-4::before {
  left: 42px;
  content: '·';
  color: #93c5fd;
}
.chapter-body .note {
  margin-top: 12px;
  padding: 12px 16px;
  background: linear-gradient(135deg, #fff7ed, #fffbeb);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  color: #92400e;
  border-left: 3px solid var(--warning);
}

/* ===== FAQ ===== */
.faq-item {
  background: var(--bg-card);
  border-radius: var(--radius);
  margin-bottom: 12px;
  border: 1px solid var(--border);
  overflow: hidden;
}
.faq-question {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 24px;
  cursor: pointer;
  font-weight: 600;
  font-size: 1rem;
  color: var(--primary);
  user-select: none;
  transition: var(--transition);
}
.faq-question:hover {
  background: rgba(37, 99, 235, 0.03);
}
.faq-question .toggle-icon {
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: var(--bg);
  transition: var(--transition);
  font-size: 0.8rem;
  color: var(--text-light);
  flex-shrink: 0;
}
.faq-item.open .faq-question .toggle-icon {
  transform: rotate(180deg);
  background: var(--accent);
  color: #fff;
}
.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease, padding 0.4s ease;
  padding: 0 24px;
  color: var(--text-light);
  font-size: 0.95rem;
  line-height: 1.8;
}
.faq-answer p + p {
  margin-top: 10px;
}
.faq-item.open .faq-answer {
  max-height: 1200px;
  padding: 0 24px 20px;
}

/* ===== Contact Form ===== */
.contact-form {
  max-width: 600px;
  margin: 0 auto;
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 40px;
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
}
.form-group {
  margin-bottom: 20px;
}
.form-group label {
  display: block;
  font-weight: 600;
  margin-bottom: 6px;
  font-size: 0.9rem;
  color: var(--primary);
}
.form-group input,
.form-group textarea {
  width: 100%;
  padding: 12px 16px;
  border: 2px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 1rem;
  transition: var(--transition);
  font-family: inherit;
  background: var(--bg);
}
.form-group input:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
  background: #fff;
}
.form-group textarea {
  min-height: 120px;
  resize: vertical;
}
.form-submit {
  width: 100%;
  padding: 14px;
  background: var(--gradient-accent);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
}
.form-submit:hover {
  box-shadow: 0 8px 24px rgba(37, 99, 235, 0.3);
  transform: translateY(-2px);
}
.form-status {
  margin-top: 16px;
  padding: 12px;
  border-radius: var(--radius-sm);
  text-align: center;
  display: none;
  font-weight: 500;
}
.form-status.success {
  display: block;
  background: #ecfdf5;
  color: #065f46;
  border: 1px solid #a7f3d0;
}
.form-status.error {
  display: block;
  background: #fef2f2;
  color: #991b1b;
  border: 1px solid #fecaca;
}

/* ===== Contact QR Card ===== */
.contact-qr-wrap {
  max-width: 680px;
  margin: 0 auto;
}
.contact-qr-card {
  position: relative;
  background: linear-gradient(145deg, #ffffff 0%, #f8fbff 100%);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 36px 28px;
  text-align: center;
  overflow: hidden;
}
.contact-qr-card::before {
  content: "";
  position: absolute;
  top: -80px;
  right: -60px;
  width: 180px;
  height: 180px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(37, 99, 235, 0.14), rgba(37, 99, 235, 0));
  pointer-events: none;
}
.contact-qr-kicker {
  display: inline-block;
  padding: 6px 12px;
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--accent);
  background: rgba(37, 99, 235, 0.1);
  border-radius: 999px;
  margin-bottom: 14px;
}
.contact-qr-card h3 {
  font-size: 1.35rem;
  margin-bottom: 10px;
  color: var(--primary);
}
.contact-qr-desc {
  color: var(--text-light);
  margin: 0 auto 20px;
  max-width: 520px;
}
.contact-qr-image-box {
  width: fit-content;
  margin: 0 auto 14px;
  padding: 10px;
  border-radius: 16px;
  background: #fff;
  border: 1px solid #dbe7ff;
  box-shadow: 0 10px 24px rgba(15, 23, 42, 0.08);
}
.contact-qr-image {
  display: block;
  width: min(280px, 70vw);
  height: auto;
  border-radius: 10px;
}
.contact-qr-note {
  display: inline-block;
  margin: 0 auto;
  font-size: 0.95rem;
  font-weight: 600;
  color: #b45309;
  background: #fffbeb;
  border: 1px dashed #f59e0b;
  border-radius: 10px;
  padding: 8px 12px;
}
#contact.section {
  padding-bottom: 40px;
}

/* ===== Testimonials ===== */
.testimonials-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}
.testimonial-card {
  margin: 0;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 14px;
  overflow: hidden;
  box-shadow: 0 8px 20px rgba(15, 23, 42, 0.08);
}
.testimonial-image {
  display: block;
  width: 100%;
  height: auto;
}

/* ===== About Me Section ===== */
.about-me-section {
  padding: 44px 0;
}
.about-me-panel {
  --about-me-side-gap: 22px;
  display: grid;
  grid-template-columns: minmax(240px, 340px) 1fr;
  gap: 22px;
  align-items: center;
  width: min(100%, 735px);
  margin: 0 auto;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 22px;
}
.about-me-photo-wrap {
  display: flex;
  justify-content: flex-start;
  padding-left: var(--about-me-side-gap);
}
.about-me-photo {
  width: 100%;
  max-width: 285px;
  border-radius: 14px;
  border: 1px solid #dbe7ff;
  box-shadow: 0 12px 28px rgba(15, 23, 42, 0.18);
}
.about-me-text h3 {
  font-size: 1.5rem;
  color: var(--primary);
  margin-bottom: 12px;
  text-align: center;
}
.about-me-text p {
  color: var(--text-light);
  line-height: 1.85;
  margin-bottom: 10px;
  text-align: center;
  padding-right: var(--about-me-side-gap);
}
.about-me-text p:last-child {
  margin-bottom: 0;
}
.about-me-story-line {
  display: block;
  margin-top: 18px;
}

/* ===== Footer ===== */
.footer {
  position: relative;
  background: linear-gradient(135deg, var(--primary), #1d4ed8);
  color: rgba(255,255,255,0.78);
  padding: 24px 0 14px;
  margin-top: 20px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 40px;
}
@media (max-width: 768px) {
  .footer-grid {
    grid-template-columns: 1fr;
    gap: 24px;
  }
}
.footer h4 {
  color: #fff;
  margin-bottom: 16px;
  font-size: 1.05rem;
}
.footer p, .footer a {
  font-size: 0.9rem;
  line-height: 2;
  color: rgba(255,255,255,0.6);
}
.footer a:hover {
  color: #fff;
}
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.12);
  padding-top: 10px;
  text-align: center;
  font-size: 0.85rem;
}
.footer-registry {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
  justify-content: center;
}
.footer-registry-link {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  white-space: nowrap;
}
.footer-registry-icon {
  width: 18px;
  height: 18px;
  flex: 0 0 auto;
}
.footer::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: linear-gradient(90deg, #60a5fa, #93c5fd, #bfdbfe);
}

/* ===== Animations ===== */
.fade-in {
  opacity: 0;
  transform: translateY(20px);
  animation: fadeIn 0.6s ease forwards;
}
.fade-in:nth-child(2) { animation-delay: 0.1s; }
.fade-in:nth-child(3) { animation-delay: 0.2s; }
.fade-in:nth-child(4) { animation-delay: 0.3s; }

@keyframes fadeIn {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ===== Scrollbar ===== */
::-webkit-scrollbar {
  width: 8px;
}
::-webkit-scrollbar-track {
  background: var(--bg);
}
::-webkit-scrollbar-thumb {
  background: #cbd5e1;
  border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
  background: #94a3b8;
}

/* ===== About Page ===== */
.about-hero {
  padding: calc(var(--nav-height) + 60px) 0 60px;
  background: var(--gradient);
  color: #fff;
  text-align: center;
}
.about-content {
  max-width: 800px;
  margin: 0 auto;
}
.about-layout {
  max-width: 980px;
}
.about-lecturer-card,
.about-course-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 28px;
}
.about-lecturer-card {
  margin-bottom: 24px;
}
.lecturer-media {
  display: flex;
  justify-content: center;
  margin: 8px 0 18px;
}
.lecturer-photo {
  width: min(360px, 100%);
  border-radius: 14px;
  border: 1px solid #dbe7ff;
  box-shadow: 0 10px 30px rgba(15, 23, 42, 0.18);
}
.about-content h2 {
  font-size: 1.5rem;
  color: var(--primary);
  margin-top: 32px;
  margin-bottom: 16px;
}
.about-lecturer-card h2,
.about-course-card > h2 {
  margin-top: 0;
}
.about-content p {
  color: var(--text-light);
  line-height: 1.8;
  margin-bottom: 16px;
}

/* ===== Misc Mobile Optimizations ===== */
@media (max-width: 480px) {
  .testimonials-grid { grid-template-columns: 1fr; }
  .hero h1 { font-size: 1.35rem; }
  .contact-form { padding: 24px; }
  .contact-qr-card { padding: 26px 18px; }
  .contact-qr-card h3 { font-size: 1.15rem; }
  .contact-qr-note { font-size: 0.88rem; }
  .about-me-panel {
    grid-template-columns: 1fr;
    gap: 18px;
    padding: 18px 14px;
  }
  .about-me-photo-wrap,
  .about-me-text p {
    padding-left: 0;
    padding-right: 0;
  }
  .about-me-photo-wrap {
    justify-content: center;
  }
  .about-me-photo {
    display: block;
    margin: 0 auto;
  }
  .about-me-section { padding: 36px 0; }
  .about-me-text h3 { font-size: 1.25rem; }
  .chapter-header { padding: 16px; }
  .chapter-body { padding: 0 16px; }
  .chapter.open .chapter-body { padding: 0 16px 16px; }
  .faq-question { padding: 16px; }
  .faq-item.open .faq-answer { padding: 0 16px 16px; }
  .about-hero { padding: calc(var(--nav-height) + 40px) 0 40px; }
  .about-hero h1 { font-size: 1.5rem; }
  .about-lecturer-card,
  .about-course-card { padding: 20px 16px; }
  .format-grid { gap: 10px; }
  .format-item { padding: 16px; }
  .format-item .emoji { font-size: 1.5rem; }
  .footer {
    padding: 20px 0 12px;
    margin-top: 16px;
  }
  .navbar-brand { font-size: 1rem; }
  .navbar-brand .brand-icon { width: 30px; height: 30px; font-size: 1rem; }
  section[style*="padding"] h1[style*="font-size"] { font-size: 1.5rem !important; }
  .chapters-grid { grid-template-columns: repeat(2, 1fr) !important; }
  .chapters-grid .card { padding: 16px; }
  .faq-cta-block { padding: 24px 16px !important; }
}

@media (max-width: 350px) {
  .hero h1 { font-size: 1.15rem; }
  .hero-meta { gap: 16px; }
  .hero-meta-item .num { font-size: 1.1rem; }
  .format-grid { grid-template-columns: 1fr 1fr; }
  .chapters-grid { grid-template-columns: 1fr 1fr !important; }
}