@import url('https://fonts.googleapis.com/css2?family=Noto+Serif+SC:wght@400;500;600;700;900&family=ZCOOL+XiaoWei&display=swap');

*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --primary: #ff6b35;
  --primary-dark: #e55a2b;
  --secondary: #ffc107;
  --secondary-dark: #e0a800;
  --bg-light: #fff3e0;
  --bg-warm: #ffe0b2;
  --bg-cream: #fff8f0;
  --text-dark: #3e2723;
  --text-medium: #5d4037;
  --text-light: #8d6e63;
  --white: #ffffff;
  --shadow-sm: 0 2px 8px rgba(255, 107, 53, 0.1);
  --shadow-md: 0 4px 20px rgba(255, 107, 53, 0.15);
  --shadow-lg: 0 8px 40px rgba(255, 107, 53, 0.2);
  --radius-sm: 8px;
  --radius-md: 16px;
  --radius-lg: 24px;
  --transition: all 0.3s ease;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Noto Serif SC', 'PingFang SC', 'Microsoft YaHei', serif;
  background-color: var(--bg-cream);
  color: var(--text-dark);
  line-height: 1.8;
  min-height: 100vh;
}

h1, h2, h3, h4, h5 {
  font-family: 'ZCOOL XiaoWei', 'Noto Serif SC', serif;
  color: var(--text-dark);
  line-height: 1.3;
}

a {
  color: var(--primary);
  text-decoration: none;
  transition: var(--transition);
}

a:hover {
  color: var(--primary-dark);
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* ============ Header / Nav ============ */
.site-header {
  background: linear-gradient(135deg, var(--white) 0%, var(--bg-light) 100%);
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 0;
  z-index: 1000;
}

.nav-wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  max-width: 1200px;
  margin: 0 auto;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: 'ZCOOL XiaoWei', serif;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary);
}

.logo-icon {
  width: 40px;
  height: 40px;
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 1.2rem;
  box-shadow: var(--shadow-sm);
}

.main-nav {
  display: flex;
  gap: 8px;
  list-style: none;
}

.main-nav a {
  display: block;
  padding: 10px 18px;
  border-radius: var(--radius-sm);
  color: var(--text-dark);
  font-weight: 500;
  transition: var(--transition);
}

.main-nav a:hover,
.main-nav a.active {
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  color: var(--white);
  box-shadow: var(--shadow-sm);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}

.nav-toggle span {
  width: 28px;
  height: 3px;
  background: var(--primary);
  border-radius: 3px;
  transition: var(--transition);
}

/* ============ Hero Section ============ */
.hero {
  position: relative;
  background: linear-gradient(135deg, #fff3e0 0%, #ffe0b2 40%, #ffd180 100%);
  padding: 80px 20px 100px;
  overflow: hidden;
  text-align: center;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(255, 193, 7, 0.3) 0%, transparent 70%);
  border-radius: 50%;
  animation: float 8s ease-in-out infinite;
}

.hero::after {
  content: '';
  position: absolute;
  bottom: -30%;
  left: -10%;
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, rgba(255, 107, 53, 0.2) 0%, transparent 70%);
  border-radius: 50%;
  animation: float 10s ease-in-out infinite reverse;
}

@keyframes float {
  0%, 100% { transform: translate(0, 0); }
  50% { transform: translate(30px, -30px); }
}

.sun-burst {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 800px;
  height: 800px;
  background:
    conic-gradient(
      from 0deg,
      transparent 0deg,
      rgba(255, 193, 7, 0.08) 10deg,
      transparent 20deg,
      transparent 40deg,
      rgba(255, 193, 7, 0.08) 50deg,
      transparent 60deg,
      transparent 80deg,
      rgba(255, 193, 7, 0.08) 90deg,
      transparent 100deg,
      transparent 120deg,
      rgba(255, 193, 7, 0.08) 130deg,
      transparent 140deg,
      transparent 160deg,
      rgba(255, 193, 7, 0.08) 170deg,
      transparent 180deg,
      transparent 200deg,
      rgba(255, 193, 7, 0.08) 210deg,
      transparent 220deg,
      transparent 240deg,
      rgba(255, 193, 7, 0.08) 250deg,
      transparent 260deg,
      transparent 280deg,
      rgba(255, 193, 7, 0.08) 290deg,
      transparent 300deg,
      transparent 320deg,
      rgba(255, 193, 7, 0.08) 330deg,
      transparent 340deg
    );
  animation: spin 60s linear infinite;
  pointer-events: none;
  z-index: 0;
}

@keyframes spin {
  to { transform: translate(-50%, -50%) rotate(360deg); }
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
  margin: 0 auto;
}

.hero-badge {
  display: inline-block;
  background: rgba(255, 255, 255, 0.9);
  color: var(--primary);
  padding: 6px 20px;
  border-radius: 999px;
  font-size: 0.9rem;
  font-weight: 600;
  margin-bottom: 24px;
  box-shadow: var(--shadow-sm);
}

.hero h1 {
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 900;
  margin-bottom: 20px;
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  font-size: 1.15rem;
  color: var(--text-medium);
  margin-bottom: 36px;
  line-height: 1.9;
}

.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: 999px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: var(--transition);
  text-decoration: none;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: var(--white);
  box-shadow: var(--shadow-md);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  color: var(--white);
}

.btn-secondary {
  background: var(--white);
  color: var(--primary);
  border: 2px solid var(--primary);
}

.btn-secondary:hover {
  background: var(--primary);
  color: var(--white);
  transform: translateY(-2px);
}

.btn-gold {
  background: linear-gradient(135deg, var(--secondary) 0%, var(--secondary-dark) 100%);
  color: var(--white);
  box-shadow: var(--shadow-md);
}

.btn-gold:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  color: var(--white);
}

/* ============ Section Title ============ */
.section-title {
  text-align: center;
  margin-bottom: 50px;
}

.section-title h2 {
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  font-weight: 900;
  margin-bottom: 12px;
  position: relative;
  display: inline-block;
}

.section-title h2::after {
  content: '';
  display: block;
  width: 60px;
  height: 4px;
  background: linear-gradient(90deg, var(--primary), var(--secondary));
  border-radius: 2px;
  margin: 12px auto 0;
}

.section-title p {
  color: var(--text-light);
  font-size: 1.05rem;
}

/* ============ Cards ============ */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 24px;
}

.card {
  background: var(--white);
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
  border: 1px solid rgba(255, 107, 53, 0.1);
}

.card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
}

.card-img {
  position: relative;
  overflow: hidden;
  aspect-ratio: 16 / 10;
  background: var(--bg-light);
}

.card-img img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.5s ease;
}

.card:hover .card-img img {
  transform: scale(1.05);
}

.card-tag {
  position: absolute;
  top: 12px;
  left: 12px;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  color: var(--white);
  padding: 4px 14px;
  border-radius: 999px;
  font-size: 0.8rem;
  font-weight: 600;
}

.card-body {
  padding: 24px;
}

.card-body h3 {
  font-size: 1.2rem;
  margin-bottom: 10px;
  line-height: 1.5;
}

.card-body h3 a {
  color: var(--text-dark);
}

.card-body h3 a:hover {
  color: var(--primary);
}

.card-body p {
  color: var(--text-light);
  font-size: 0.95rem;
  margin-bottom: 16px;
  line-height: 1.7;
}

.card-meta {
  display: flex;
  align-items: center;
  gap: 16px;
  font-size: 0.85rem;
  color: var(--text-light);
}

.card-meta span {
  display: flex;
  align-items: center;
  gap: 4px;
}

/* ============ Feature Cards (Index) ============ */
.features {
  background: var(--bg-cream);
  padding: 80px 20px;
}

.feature-card {
  background: var(--white);
  border-radius: var(--radius-md);
  padding: 36px 28px;
  text-align: center;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
  border-top: 4px solid transparent;
}

.feature-card:hover {
  transform: translateY(-6px);
  border-top-color: var(--primary);
  box-shadow: var(--shadow-lg);
}

.feature-icon {
  width: 70px;
  height: 70px;
  margin: 0 auto 20px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2rem;
  background: linear-gradient(135deg, var(--bg-light), var(--bg-warm));
}

.feature-card h3 {
  font-size: 1.3rem;
  margin-bottom: 12px;
}

.feature-card p {
  color: var(--text-light);
  font-size: 0.95rem;
}

/* ============ Topics Section ============ */
.topics-section {
  background: linear-gradient(135deg, var(--bg-light) 0%, var(--bg-cream) 100%);
  padding: 80px 20px;
}

.topic-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 20px;
}

.topic-item {
  background: var(--white);
  border-radius: var(--radius-md);
  padding: 24px;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
  display: flex;
  align-items: flex-start;
  gap: 16px;
}

.topic-item:hover {
  transform: translateX(6px);
  box-shadow: var(--shadow-md);
}

.topic-rank {
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  color: var(--white);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.1rem;
}

.topic-item:nth-child(1) .topic-rank { background: linear-gradient(135deg, #ff6b35, #ff3d00); }
.topic-item:nth-child(2) .topic-rank { background: linear-gradient(135deg, #ffc107, #ff9100); }
.topic-item:nth-child(3) .topic-rank { background: linear-gradient(135deg, #ffb74d, #f57c00); }

.topic-content h4 {
  font-size: 1.1rem;
  margin-bottom: 6px;
}

.topic-meta {
  display: flex;
  gap: 12px;
  font-size: 0.85rem;
  color: var(--text-light);
}

/* ============ Charity CTA ============ */
.charity-cta {
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  padding: 80px 20px;
  text-align: center;
  color: var(--white);
}

.charity-cta h2 {
  color: var(--white);
  font-size: clamp(1.8rem, 4vw, 2.5rem);
  margin-bottom: 16px;
}

.charity-cta p {
  font-size: 1.1rem;
  margin-bottom: 36px;
  opacity: 0.95;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.charity-cta .btn-primary {
  background: var(--white);
  color: var(--primary);
}

.charity-cta .btn-primary:hover {
  background: var(--bg-cream);
}

/* ============ Filter Bar ============ */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: center;
  margin-bottom: 40px;
}

.filter-btn {
  padding: 8px 24px;
  border: 2px solid var(--primary);
  border-radius: 999px;
  background: transparent;
  color: var(--primary);
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
}

.filter-btn:hover,
.filter-btn.active {
  background: var(--primary);
  color: var(--white);
}

/* ============ Person Card (Positive) ============ */
.person-card {
  background: var(--white);
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
  display: flex;
  flex-direction: column;
}

.person-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
}

.person-avatar {
  width: 100%;
  aspect-ratio: 4/5;
  background: linear-gradient(135deg, var(--bg-light), var(--bg-warm));
  overflow: hidden;
}

.person-avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.person-info {
  padding: 24px;
  text-align: center;
}

.person-info h3 {
  font-size: 1.3rem;
  margin-bottom: 8px;
}

.person-title {
  color: var(--primary);
  font-weight: 600;
  font-size: 0.95rem;
  margin-bottom: 12px;
}

.person-info p {
  color: var(--text-light);
  font-size: 0.9rem;
  line-height: 1.7;
}

/* ============ Charity Project Card ============ */
.charity-card {
  background: var(--white);
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

.charity-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.charity-header {
  position: relative;
  aspect-ratio: 16/9;
  overflow: hidden;
}

.charity-header img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.charity-badge {
  position: absolute;
  bottom: 16px;
  left: 16px;
  background: rgba(255, 255, 255, 0.95);
  color: var(--primary);
  padding: 6px 16px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.9rem;
}

.charity-body {
  padding: 28px;
}

.charity-body h3 {
  font-size: 1.3rem;
  margin-bottom: 12px;
}

.charity-body p {
  color: var(--text-light);
  font-size: 0.95rem;
  margin-bottom: 20px;
  line-height: 1.7;
}

.progress-wrap {
  margin-bottom: 16px;
}

.progress-bar {
  height: 8px;
  background: var(--bg-light);
  border-radius: 4px;
  overflow: hidden;
  margin-bottom: 8px;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary), var(--secondary));
  border-radius: 4px;
  transition: width 0.6s ease;
}

.progress-info {
  display: flex;
  justify-content: space-between;
  font-size: 0.85rem;
  color: var(--text-light);
}

.charity-stats {
  display: flex;
  justify-content: space-around;
  padding: 20px 0;
  border-top: 1px solid var(--bg-light);
}

.charity-stat {
  text-align: center;
}

.charity-stat .num {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary);
}

.charity-stat .label {
  font-size: 0.85rem;
  color: var(--text-light);
}

/* ============ Stats Section ============ */
.stats-section {
  background: var(--bg-cream);
  padding: 60px 20px;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 30px;
  text-align: center;
}

.stat-item {
  padding: 20px;
}

.stat-item .num {
  font-size: 3rem;
  font-weight: 900;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.stat-item .label {
  color: var(--text-light);
  font-size: 1rem;
  margin-top: 8px;
}

/* ============ Content Page (About) ============ */
.content-page {
  padding: 60px 20px;
}

.content-section {
  max-width: 800px;
  margin: 0 auto 60px;
}

.content-section h2 {
  font-size: 2rem;
  margin-bottom: 20px;
  color: var(--primary);
}

.content-section p {
  font-size: 1.05rem;
  color: var(--text-medium);
  line-height: 2;
  margin-bottom: 16px;
}

.team-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 30px;
  margin-top: 40px;
}

.team-member {
  text-align: center;
}

.team-avatar {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--bg-light), var(--bg-warm));
  margin: 0 auto 16px;
  overflow: hidden;
  border: 4px solid var(--white);
  box-shadow: var(--shadow-md);
}

.team-avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.team-member h3 {
  font-size: 1.2rem;
  margin-bottom: 6px;
}

.team-role {
  color: var(--primary);
  font-weight: 600;
  font-size: 0.9rem;
  margin-bottom: 8px;
}

.team-member p {
  color: var(--text-light);
  font-size: 0.9rem;
}

/* ============ Contact Form ============ */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 50px;
  max-width: 1100px;
  margin: 0 auto;
}

.contact-info h2,
.contact-form h2 {
  font-size: 1.8rem;
  margin-bottom: 24px;
}

.contact-list {
  list-style: none;
}

.contact-list li {
  display: flex;
  gap: 16px;
  padding: 20px;
  background: var(--white);
  border-radius: var(--radius-md);
  margin-bottom: 16px;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

.contact-list li:hover {
  transform: translateX(6px);
  box-shadow: var(--shadow-md);
}

.contact-icon {
  width: 48px;
  height: 48px;
  flex-shrink: 0;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--white);
  font-size: 1.3rem;
}

.contact-list h4 {
  font-size: 1.05rem;
  margin-bottom: 4px;
}

.contact-list p {
  color: var(--text-light);
  font-size: 0.95rem;
}

.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: block;
  margin-bottom: 8px;
  font-weight: 500;
  color: var(--text-dark);
}

.form-group input,
.form-group select,
.form-group textarea {
  width: 100%;
  padding: 12px 16px;
  border: 2px solid var(--bg-warm);
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-family: inherit;
  background: var(--white);
  color: var(--text-dark);
  transition: var(--transition);
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(255, 107, 53, 0.1);
}

.form-group textarea {
  min-height: 140px;
  resize: vertical;
}

/* ============ Pagination ============ */
.pagination {
  display: flex;
  justify-content: center;
  gap: 8px;
  margin-top: 40px;
}

.pagination a,
.pagination span {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 40px;
  height: 40px;
  padding: 0 12px;
  border-radius: var(--radius-sm);
  background: var(--white);
  color: var(--text-dark);
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
  font-weight: 500;
}

.pagination a:hover,
.pagination .current {
  background: var(--primary);
  color: var(--white);
}

/* ============ Footer ============ */
.site-footer {
  background: linear-gradient(180deg, var(--text-dark) 0%, #2d1810 100%);
  color: var(--bg-light);
  padding: 60px 20px 0;
}

.footer-grid {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1fr;
  gap: 40px;
  padding-bottom: 40px;
}

.footer-col h4 {
  color: var(--white);
  font-size: 1.1rem;
  margin-bottom: 20px;
  position: relative;
  padding-bottom: 10px;
}

.footer-col h4::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 30px;
  height: 3px;
  background: linear-gradient(90deg, var(--primary), var(--secondary));
  border-radius: 2px;
}

.footer-col p {
  color: var(--bg-warm);
  font-size: 0.95rem;
  line-height: 1.8;
  margin-bottom: 20px;
}

.footer-col ul {
  list-style: none;
}

.footer-col ul li {
  margin-bottom: 10px;
}

.footer-col ul li a {
  color: var(--bg-warm);
  font-size: 0.95rem;
  transition: var(--transition);
}

.footer-col ul li a:hover {
  color: var(--secondary);
  padding-left: 6px;
}

.social-links {
  display: flex;
  gap: 12px;
  margin-top: 20px;
}

.social-links a {
  width: 40px;
  height: 40px;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--white);
  transition: var(--transition);
}

.social-links a:hover {
  background: var(--primary);
  transform: translateY(-3px);
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding: 24px 20px;
  text-align: center;
  font-size: 0.9rem;
  color: var(--bg-warm);
}

/* ============ Page Banner ============ */
.page-banner {
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  padding: 60px 20px;
  text-align: center;
  color: var(--white);
}

.page-banner h1 {
  font-size: clamp(2rem, 4vw, 2.8rem);
  color: var(--white);
  margin-bottom: 10px;
}

.page-banner p {
  font-size: 1.1rem;
  opacity: 0.95;
}

.breadcrumb {
  margin-top: 16px;
  font-size: 0.9rem;
  opacity: 0.85;
}

.breadcrumb a {
  color: var(--white);
  opacity: 0.85;
}

.breadcrumb a:hover {
  opacity: 1;
}

.breadcrumb span {
  margin: 0 8px;
}

/* ============ Responsive ============ */
@media (max-width: 968px) {
  .contact-grid {
    grid-template-columns: 1fr;
  }

  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 768px) {
  .nav-toggle {
    display: flex;
  }

  .main-nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--white);
    flex-direction: column;
    padding: 20px;
    box-shadow: var(--shadow-md);
    gap: 4px;
  }

  .main-nav.open {
    display: flex;
  }

  .main-nav a {
    padding: 14px 18px;
  }

  .hero {
    padding: 60px 20px 80px;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 30px;
  }

  .card-grid {
    grid-template-columns: 1fr;
  }

  .topic-list {
    grid-template-columns: 1fr;
  }

  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .hero-actions {
    flex-direction: column;
    align-items: center;
  }

  .btn {
    width: 100%;
    max-width: 280px;
    justify-content: center;
  }
}

@media (max-width: 480px) {
  .stats-grid {
    grid-template-columns: 1fr;
  }

  .nav-wrap {
    padding: 12px 16px;
  }

  .logo {
    font-size: 1.2rem;
  }
}

/* ============ Back to Top ============ */
.back-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 48px;
  height: 48px;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  color: var(--white);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  box-shadow: var(--shadow-md);
  transition: var(--transition);
  z-index: 999;
  border: none;
  font-size: 1.2rem;
}

.back-top:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

/* ============ Utilities ============ */
.section-padding {
  padding: 80px 20px;
}

.section-padding-sm {
  padding: 50px 20px;
}

.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mt-20 { margin-top: 20px; }
.mt-30 { margin-top: 30px; }
.mb-20 { margin-bottom: 20px; }
.mb-30 { margin-bottom: 30px; }

.fade-in {
  animation: fadeIn 0.6s ease;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}