:root {
  --color-primary: #4A6CF7;
  --color-dark: #1a1a2e;
  --color-text: #333;
  --color-muted: #666;
  --color-light-bg: #f5f7fa;
  --radius: 16px;
  --shadow: 0 4px 20px rgba(0,0,0,0.05);
  --navbar-height: 70px;
}

html {
  scroll-behavior: smooth;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color: var(--color-text);
  line-height: 1.6;
  background: var(--color-light-bg);
}

a:focus-visible,
button:focus-visible,
[role="button"]:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 40px;
  height: var(--navbar-height);
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  transition: box-shadow 0.3s;
}

.navbar.scrolled {
  box-shadow: 0 2px 20px rgba(0,0,0,0.08);
}

.navbar .logo img {
  height: 40px;
  width: auto;
  object-fit: contain;
}

.nav-menu {
  display: flex;
  gap: 32px;
}

.nav-menu a {
  text-decoration: none;
  color: #555;
  font-weight: 500;
  font-size: 15px;
  transition: color 0.2s;
  position: relative;
}

.nav-menu a:hover,
.nav-menu a.active {
  color: var(--color-primary);
}

.nav-menu a.active::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--color-primary);
}

.banner {
  padding: 140px 20px 80px;
  text-align: center;
  background: linear-gradient(135deg, #eef3ff 0%, #ffffff 100%);
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
}

.banner-content h1 {
  font-size: 56px;
  font-weight: 700;
  color: var(--color-dark);
  margin-bottom: 16px;
}

.banner-content p {
  font-size: 20px;
  color: var(--color-muted);
  margin-bottom: 32px;
}

.banner-buttons {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

.btn-primary {
  padding: 14px 40px;
  background: var(--color-primary);
  color: #fff;
  border: none;
  border-radius: 50px;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.3s, transform 0.2s;
}

.btn-primary:hover {
  background: #3a5ce5;
  transform: translateY(-2px);
}

.btn-second {
  padding: 14px 40px;
  background: transparent;
  color: var(--color-primary);
  border: 2px solid var(--color-primary);
  border-radius: 50px;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.3s, color 0.3s;
}

.btn-second:hover {
  background: var(--color-primary);
  color: #fff;
}

.section {
  padding: 80px 20px;
}

.section.dark-section {
  background: var(--color-dark);
  color: #fff;
}

.section-title {
  text-align: center;
  font-size: 36px;
  font-weight: 700;
  margin-bottom: 48px;
}

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

.advantage-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 30px;
}

.advantage-list .item {
  background: #fff;
  padding: 32px 24px;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  text-align: center;
  transition: transform 0.3s;
}

.advantage-list .item:hover {
  transform: translateY(-4px);
}

.advantage-list .item h3 {
  font-size: 20px;
  margin-bottom: 12px;
  color: var(--color-dark);
}

.advantage-list .item p {
  color: var(--color-muted);
  font-size: 14px;
}

.course-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 30px;
}

.course-card {
  background: #fff;
  border-radius: var(--radius);
  padding: 32px 24px;
  text-align: center;
  box-shadow: var(--shadow);
  cursor: pointer;
  transition: transform 0.3s, box-shadow 0.3s;
}

.course-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 8px 30px rgba(0,0,0,0.1);
}

.course-card .card-img {
  margin-bottom: 16px;
}

.course-card .card-img img {
  width: 100%;
  height: 180px;
  object-fit: cover;
  border-radius: 12px;
  background: #f0f0f0;
}

.course-card h3 {
  font-size: 20px;
  margin-bottom: 10px;
  color: var(--color-dark);
}

.course-card p {
  color: var(--color-muted);
  font-size: 14px;
  margin-bottom: 16px;
}

.course-card .price {
  display: inline-block;
  padding: 6px 20px;
  background: var(--color-primary);
  color: #fff;
  border-radius: 50px;
  font-size: 14px;
  font-weight: 600;
}

.partner-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
  gap: 16px;
}

.partner-item {
  background: #fff;
  padding: 12px;
  border-radius: 8px;
  text-align: center;
  font-size: 14px;
  cursor: pointer;
  box-shadow: 0 2px 8px rgba(0,0,0,.05);
  transition: .2s;
  user-select: none;
}

.partner-item:hover {
  background: #f0f4ff;
  transform: translateY(-2px);
}

.partner-item.active {
  background: var(--color-primary);
  color: #fff;
}

.mentor-overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0.5);
  z-index: 3000;
  justify-content: center;
  align-items: center;
}

.mentor-popup {
  position: relative;
  width: 520px;
  max-width: 90%;
  background: #fff;
  border-radius: 20px;
  padding: 24px;
  box-shadow: 0 20px 60px rgba(0,0,0,.25);
}

.popup-content {
  display: flex;
  gap: 20px;
}

.popup-photo img {
  width: 150px;
  height: 200px;
  object-fit: cover;
  object-position: center;
  border-radius: 12px;
  background: #f0f0f0;
}

.popup-info {
  flex: 1;
}

.popup-info h3 {
  font-size: 24px;
  margin-bottom: 12px;
  color: var(--color-dark);
}

.popup-title {
  color: var(--color-primary);
  font-weight: 600;
  margin-bottom: 10px;
}

.popup-info p {
  line-height: 1.8;
  color: var(--color-muted);
}

.close-popup {
  position: absolute;
  right: 16px;
  top: 10px;
  font-size: 28px;
  cursor: pointer;
  color: #999;
  background: none;
  border: none;
  padding: 0;
  line-height: 1;
}

.close-popup:hover {
  color: #333;
}

.modal {
  display: none;
  position: fixed;
  z-index: 9999;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0,0,0,0.5);
  justify-content: center;
  align-items: center;
}

.modal-content {
  background-color: white;
  padding: 30px;
  border-radius: 16px;
  text-align: center;
  position: relative;
  max-width: 400px;
  width: 90%;
}

.close-btn {
  position: absolute;
  right: 15px;
  top: 10px;
  font-size: 24px;
  cursor: pointer;
  color: #666;
  background: none;
  border: none;
  padding: 0;
  line-height: 1;
}

.modal-text {
  margin-bottom: 20px;
  font-size: 16px;
  color: #333;
}

.qr-wrapper img {
  width: 200px;
  height: 200px;
  margin: 0 auto;
  object-fit: contain;
  background: #f0f0f0;
}

.qr-tip {
  margin-top: 10px;
  color: #666;
  font-size: 14px;
}

.footer {
  background: var(--color-dark);
  color: #aaa;
  padding: 40px 20px;
}

.footer-content {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 24px;
}

.footer-left h3 {
  color: #fff;
  font-size: 24px;
  margin-bottom: 8px;
}

.footer-right {
  display: flex;
  gap: 24px;
  flex-wrap: wrap;
}

.footer-right a {
  color: #aaa;
  text-decoration: none;
  transition: color 0.2s;
}

.footer-right a:hover {
  color: var(--color-primary);
}

@media (max-width: 480px) {
  .popup-content {
    flex-direction: column;
    align-items: center;
    text-align: center;
  }
  .popup-photo img {
    width: 120px;
    height: 160px;
  }
  .banner-content h1 {
    font-size: 36px;
  }
  .banner-content p {
    font-size: 16px;
  }
  .course-card .card-img img {
    height: 140px;
  }
}