:root {
  --primary-color: #0056b3;
  --bg-color: #87CEEB; /* Sky blue as requested */
  --text-color: #333333;
  --glass-bg: rgba(255, 255, 255, 0.75);
  --glass-border: rgba(255, 255, 255, 0.4);
  --glass-shadow: 0 8px 32px 0 rgba(31, 38, 135, 0.15);
}

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

body {
  font-family: 'KaiTi', 'STKaiti', 'BiauKai', 'KaiTi_GB2312', serif; /* 正楷字 */
  background: var(--bg-color);
  background: linear-gradient(135deg, #87CEEB 0%, #e0f7fa 100%);
  color: var(--text-color);
  line-height: 1.6;
  min-height: 100vh;
  overflow-x: hidden;
}

/* 玻璃拟物化通用类 */
.glass-panel {
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid var(--glass-border);
  border-radius: 16px;
  box-shadow: var(--glass-shadow);
}

/* 导航栏 */
header {
  position: fixed;
  top: 0;
  width: 100%;
  z-index: 1000;
  padding: 15px 5%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: all 0.3s ease;
}

header.scrolled {
  background: rgba(255, 255, 255, 0.9);
  box-shadow: 0 4px 15px rgba(0,0,0,0.1);
  padding: 10px 5%;
}

.logo {
  font-size: 28px;
  font-weight: bold;
  color: #0056b3;
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 10px;
}

nav ul {
  list-style: none;
  display: flex;
  gap: 25px;
}

nav ul li a {
  text-decoration: none;
  color: #333;
  font-size: 18px;
  font-weight: bold;
  transition: color 0.3s ease;
  position: relative;
}

nav ul li a::after {
  content: '';
  position: absolute;
  width: 0;
  height: 2px;
  bottom: -5px;
  left: 0;
  background-color: #0056b3;
  transition: width 0.3s ease;
}

nav ul li a:hover::after {
  width: 100%;
}

.btn-register {
  background: linear-gradient(90deg, #ff8a00, #e52e71);
  color: white;
  padding: 10px 25px;
  border-radius: 30px;
  text-decoration: none;
  font-size: 18px;
  font-weight: bold;
  box-shadow: 0 4px 15px rgba(229, 46, 113, 0.3);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.btn-register:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 20px rgba(229, 46, 113, 0.5);
  color: white;
}

/* 首页 Hero 区域 */
.hero {
  padding: 150px 5% 100px;
  text-align: center;
  position: relative;
}

.hero h1 {
  font-size: 3.5rem;
  margin-bottom: 20px;
  color: #004080;
  animation: fadeInDown 1s ease-out;
}

.hero p {
  font-size: 1.5rem;
  margin-bottom: 40px;
  color: #444;
  animation: fadeInUp 1s ease-out 0.3s backwards;
}

.hero-buttons {
  display: flex;
  justify-content: center;
  gap: 20px;
  animation: fadeInUp 1s ease-out 0.6s backwards;
}

.btn-primary {
  background: #0056b3;
  color: white;
  padding: 15px 40px;
  border-radius: 30px;
  font-size: 20px;
  text-decoration: none;
  font-weight: bold;
  transition: all 0.3s ease;
}

.btn-primary:hover {
  background: #004080;
  transform: translateY(-3px);
  box-shadow: 0 5px 15px rgba(0,86,179,0.3);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.8);
  color: #0056b3;
  padding: 15px 40px;
  border-radius: 30px;
  font-size: 20px;
  text-decoration: none;
  font-weight: bold;
  border: 2px solid #0056b3;
  transition: all 0.3s ease;
}

.btn-secondary:hover {
  background: #0056b3;
  color: white;
  transform: translateY(-3px);
}

/* 核心卖点 */
.features {
  padding: 80px 5%;
}

.section-title {
  text-align: center;
  font-size: 2.5rem;
  margin-bottom: 50px;
  color: #004080;
}

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

.feature-card {
  padding: 40px 30px;
  text-align: center;
  transition: transform 0.4s ease, box-shadow 0.4s ease;
}

.feature-card:hover {
  transform: translateY(-15px);
  box-shadow: 0 15px 40px rgba(0,0,0,0.15);
}

.feature-icon {
  font-size: 50px;
  margin-bottom: 20px;
}

.feature-card h3 {
  font-size: 1.8rem;
  margin-bottom: 15px;
  color: #0056b3;
}

.feature-card p {
  font-size: 1.1rem;
  color: #555;
}

/* 套餐购买 */
.pricing {
  padding: 80px 5%;
}

.pricing-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 40px;
  max-width: 1200px;
  margin: 0 auto;
}

.pricing-card {
  padding: 50px 30px;
  text-align: center;
  position: relative;
  overflow: hidden;
  transition: transform 0.4s ease;
}

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

.pricing-card.popular {
  border: 2px solid #ff8a00;
  transform: scale(1.05);
}
.pricing-card.popular:hover {
  transform: scale(1.08);
}

.badge {
  position: absolute;
  top: 20px;
  right: -35px;
  background: #ff8a00;
  color: white;
  padding: 5px 40px;
  transform: rotate(45deg);
  font-weight: bold;
}

.price {
  font-size: 3rem;
  font-weight: bold;
  color: #e52e71;
  margin: 20px 0;
}

.price span {
  font-size: 1.2rem;
  color: #666;
}

.pricing-features {
  list-style: none;
  margin: 30px 0;
  text-align: left;
}

.pricing-features li {
  margin-bottom: 15px;
  font-size: 1.1rem;
  display: flex;
  align-items: center;
  gap: 10px;
}

/* 用户评价 */
.reviews {
  padding: 80px 5%;
  overflow: hidden;
}

.review-slider {
  display: flex;
  gap: 30px;
  animation: slideLeft 20s linear infinite;
}

.review-slider:hover {
  animation-play-state: paused;
}

.review-card {
  min-width: 350px;
  padding: 30px;
  flex-shrink: 0;
}

.review-content {
  font-size: 1.1rem;
  font-style: italic;
  margin-bottom: 20px;
  color: #444;
}

.review-author {
  font-weight: bold;
  color: #0056b3;
  text-align: right;
}

/* FAQ */
.faq {
  padding: 80px 5%;
  max-width: 900px;
  margin: 0 auto;
}

.faq-item {
  margin-bottom: 20px;
  cursor: pointer;
}

.faq-question {
  padding: 20px;
  font-size: 1.2rem;
  font-weight: bold;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.faq-answer {
  padding: 0 20px;
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease, padding 0.3s ease;
  color: #555;
}

.faq-item.active .faq-answer {
  max-height: 200px;
  padding: 20px;
}
.faq-item.active .faq-question {
  color: #0056b3;
}

/* 文章列表 */
.articles-section {
  padding: 80px 5%;
  background: rgba(255, 255, 255, 0.5);
}

.articles-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 20px;
}

.article-link {
  display: block;
  padding: 20px;
  text-decoration: none;
  color: #333;
  transition: all 0.3s ease;
}
.article-link:hover {
  background: white;
  transform: translateY(-5px);
  color: #0056b3;
}
.article-link h4 {
  font-size: 1.2rem;
  margin-bottom: 10px;
}
.article-link p {
  font-size: 0.9rem;
  color: #666;
}

/* Footer & Keywords */
footer {
  background: #222;
  color: #fff;
  padding: 60px 5% 20px;
  margin-top: 50px;
}

.footer-keywords {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 40px;
  justify-content: center;
}

.keyword-tag {
  background: #333;
  color: #ccc;
  padding: 5px 12px;
  border-radius: 15px;
  font-size: 0.85rem;
  text-decoration: none;
  transition: background 0.3s ease;
}

.keyword-tag:hover {
  background: #0056b3;
  color: white;
}

.footer-bottom {
  text-align: center;
  border-top: 1px solid #444;
  padding-top: 20px;
  font-size: 0.9rem;
  color: #888;
}

/* Animations */
@keyframes fadeInDown {
  from { opacity: 0; transform: translateY(-30px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(30px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes slideLeft {
  from { transform: translateX(0); }
  to { transform: translateX(-100%); }
}

/* Responsive */
@media (max-width: 768px) {
  nav ul {
    display: none; /* simple mobile nav approach for now */
  }
  .hero h1 { font-size: 2.5rem; }
  .hero-buttons { flex-direction: column; }
  .pricing-card.popular { transform: scale(1); }
  .pricing-card.popular:hover { transform: scale(1.02); }
}