:root {
  --primary-color: #00BFFF;
  --primary-dark: #0088cc;
  --primary-light: rgba(0, 191, 255, 0.1);
  --bg-color: #0f172a;
  --card-bg: rgba(30, 41, 59, 0.7);
  --text-main: #f8fafc;
  --text-muted: #cbd5e1;
  --glass-border: rgba(255, 255, 255, 0.1);
}

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

body {
  font-family: "楷体", "KaiTi", "STKaiti", "BiauKai", "华文楷体", sans-serif;
  background-color: var(--bg-color);
  color: var(--text-main);
  line-height: 1.6;
  overflow-x: hidden;
  background-image: radial-gradient(circle at 15% 50%, rgba(0, 191, 255, 0.15), transparent 25%),
                    radial-gradient(circle at 85% 30%, rgba(0, 191, 255, 0.1), transparent 25%);
  background-attachment: fixed;
}

a {
  text-decoration: none;
  color: var(--primary-color);
  transition: all 0.3s ease;
}

a:hover {
  color: var(--primary-dark);
  text-shadow: 0 0 10px var(--primary-light);
}

/* Navbar */
header {
  position: fixed;
  top: 0;
  width: 100%;
  padding: 20px 50px;
  background: rgba(15, 23, 42, 0.8);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--glass-border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  z-index: 1000;
  transition: all 0.3s ease;
}

.logo {
  font-size: 28px;
  font-weight: bold;
  color: var(--primary-color);
  text-shadow: 0 0 15px rgba(0, 191, 255, 0.5);
  display: flex;
  align-items: center;
  gap: 10px;
}

.nav-links {
  display: flex;
  gap: 30px;
}

.nav-links a {
  color: var(--text-main);
  font-size: 18px;
  position: relative;
}

.nav-links a::after {
  content: '';
  position: absolute;
  width: 0;
  height: 2px;
  bottom: -5px;
  left: 0;
  background-color: var(--primary-color);
  transition: width 0.3s ease;
}

.nav-links a:hover::after {
  width: 100%;
}

.btn-register {
  background: linear-gradient(135deg, #00BFFF, #0088cc);
  color: #fff !important;
  padding: 10px 25px;
  border-radius: 30px;
  font-weight: bold;
  box-shadow: 0 4px 15px rgba(0, 191, 255, 0.4);
  transition: transform 0.3s, box-shadow 0.3s;
}

.btn-register:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0, 191, 255, 0.6);
}

/* Hero Section */
.hero {
  height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
  padding: 0 20px;
  margin-top: 60px;
}

.hero h1 {
  font-size: 64px;
  margin-bottom: 20px;
  background: linear-gradient(to right, #ffffff, #00BFFF);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  animation: fadeInDown 1s ease-out;
}

.hero p {
  font-size: 24px;
  color: var(--text-muted);
  max-width: 800px;
  margin-bottom: 40px;
  animation: fadeInUp 1s ease-out 0.5s both;
}

.hero-buttons {
  display: flex;
  gap: 20px;
  animation: fadeIn 1s ease-out 1s both;
}

.btn-primary {
  background: linear-gradient(135deg, #00BFFF, #0088cc);
  color: #fff !important;
  padding: 15px 40px;
  border-radius: 30px;
  font-size: 20px;
  font-weight: bold;
  box-shadow: 0 4px 15px rgba(0, 191, 255, 0.4);
  transition: all 0.3s ease;
  border: 1px solid transparent;
}

.btn-primary:hover {
  transform: translateY(-3px) scale(1.05);
  box-shadow: 0 8px 25px rgba(0, 191, 255, 0.6);
}

.btn-secondary {
  background: transparent;
  color: var(--primary-color) !important;
  padding: 15px 40px;
  border-radius: 30px;
  font-size: 20px;
  font-weight: bold;
  border: 2px solid var(--primary-color);
  transition: all 0.3s ease;
}

.btn-secondary:hover {
  background: var(--primary-light);
  transform: translateY(-3px);
}

/* Features */
.features {
  padding: 100px 50px;
  text-align: center;
}

.section-title {
  font-size: 42px;
  margin-bottom: 60px;
  color: var(--primary-color);
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 30px;
  max-width: 1200px;
  margin: 0 auto;
}

.feature-card {
  background: var(--card-bg);
  border: 1px solid var(--glass-border);
  border-radius: 20px;
  padding: 40px 30px;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  transition: transform 0.4s ease, box-shadow 0.4s ease;
  position: relative;
  overflow: hidden;
}

.feature-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: linear-gradient(to right, transparent, var(--primary-color), transparent);
  transform: scaleX(0);
  transition: transform 0.4s ease;
}

.feature-card:hover {
  transform: translateY(-10px);
  box-shadow: 0 15px 30px rgba(0, 0, 0, 0.5), 0 0 20px var(--primary-light);
}

.feature-card:hover::before {
  transform: scaleX(1);
}

.feature-icon {
  font-size: 50px;
  color: var(--primary-color);
  margin-bottom: 20px;
}

.feature-card h3 {
  font-size: 24px;
  margin-bottom: 15px;
}

.feature-card p {
  color: var(--text-muted);
  font-size: 16px;
}

/* Pricing */
.pricing {
  padding: 100px 50px;
  background: rgba(15, 23, 42, 0.5);
  text-align: center;
}

.pricing-grid {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 40px;
  max-width: 1200px;
  margin: 0 auto;
}

.pricing-card {
  background: #1e293b;
  border: 1px solid var(--glass-border);
  border-radius: 20px;
  width: 320px;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  transition: all 0.4s ease;
}

.pricing-card:hover {
  transform: translateY(-15px);
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.6), 0 0 15px var(--primary-light);
  border-color: var(--primary-color);
}

.pricing-header {
  padding: 30px 20px;
  background: rgba(0, 191, 255, 0.05);
  border-bottom: 1px solid var(--glass-border);
}

.badge {
  background: var(--text-main);
  color: #000;
  padding: 5px 15px;
  border-radius: 20px;
  font-weight: bold;
  font-size: 16px;
  display: inline-block;
  margin-bottom: 15px;
}

.pricing-features {
  padding: 30px 20px;
  flex-grow: 1;
  display: flex;
  flex-direction: column;
  gap: 15px;
}

.pf-item {
  background: #f8fafc;
  color: #0f172a;
  padding: 8px 15px;
  border-radius: 20px;
  font-size: 14px;
  font-weight: bold;
  display: flex;
  align-items: center;
  justify-content: center;
}

.pf-item.blue {
  color: var(--primary-color);
  box-shadow: inset 0 0 5px rgba(0,191,255,0.2);
}

.pricing-footer {
  padding: 20px;
  background: #151e2e;
  border-top: 1px solid var(--glass-border);
}

.btn-buy {
  display: block;
  width: 100%;
  padding: 12px;
  background: transparent;
  color: var(--primary-dark) !important;
  border: 1px solid var(--primary-dark);
  border-radius: 8px;
  font-weight: bold;
  transition: all 0.3s;
}

.pricing-card:hover .btn-buy {
  background: var(--primary-color);
  color: #fff !important;
  border-color: var(--primary-color);
}

/* Article List */
.articles-section {
  padding: 100px 50px;
  max-width: 1200px;
  margin: 0 auto;
}

.article-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 20px;
}

.article-item {
  background: var(--card-bg);
  padding: 20px;
  border-radius: 10px;
  border: 1px solid var(--glass-border);
  transition: all 0.3s;
}

.article-item:hover {
  border-color: var(--primary-color);
  transform: scale(1.02);
}

.article-item h4 {
  font-size: 18px;
  margin-bottom: 10px;
  color: var(--primary-color);
}

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

/* FAQ */
.faq-section {
  padding: 100px 50px;
  background: rgba(15, 23, 42, 0.5);
}

.faq-container {
  max-width: 800px;
  margin: 0 auto;
}

.faq-item {
  background: var(--card-bg);
  border: 1px solid var(--glass-border);
  border-radius: 10px;
  margin-bottom: 15px;
  padding: 20px;
  transition: all 0.3s;
}

.faq-item:hover {
  border-color: var(--primary-color);
}

.faq-question {
  font-size: 20px;
  font-weight: bold;
  color: var(--primary-color);
  margin-bottom: 10px;
}

.faq-answer {
  color: var(--text-muted);
}

/* Footer & Tags */
footer {
  padding: 60px 50px 30px;
  background: #0b1120;
  border-top: 1px solid var(--glass-border);
  text-align: center;
}

.tags-container {
  max-width: 1200px;
  margin: 0 auto 40px;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px;
}

.tag {
  font-size: 12px;
  color: var(--text-muted);
  background: rgba(255,255,255,0.05);
  padding: 5px 10px;
  border-radius: 4px;
  border: 1px solid rgba(255,255,255,0.1);
  transition: all 0.3s;
}

.tag:hover {
  color: var(--primary-color);
  border-color: var(--primary-color);
}

.copyright {
  color: #64748b;
  font-size: 14px;
}

/* 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 fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

/* Responsive */
@media (max-width: 768px) {
  header { padding: 15px 20px; }
  .nav-links { display: none; }
  .hero h1 { font-size: 42px; }
  .hero p { font-size: 18px; }
  .hero-buttons { flex-direction: column; }
  .features, .pricing, .articles-section, .faq-section { padding: 60px 20px; }
}