/* 小牛云 xiaoniuyun.xyz - Modern High-Performance Design System */
@import url('https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:wght@400;500;600;700;800&family=Noto+Sans+SC:wght@400;500;700;900&display=swap');

:root {
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --primary-light: #eff6ff;
  --primary-glow: rgba(37, 99, 235, 0.15);
  --accent: #0284c7;
  --accent-warm: #f97316;
  --text-dark: #0f172a;
  --text-muted: #64748b;
  --text-light: #94a3b8;
  --bg-page: #f8fafc;
  --bg-card: #ffffff;
  --border-light: #e2e8f0;
  --border-focus: #bfdbfe;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-full: 9999px;
  --shadow-sm: 0 2px 4px rgba(15, 23, 42, 0.04);
  --shadow-md: 0 10px 25px -5px rgba(15, 23, 42, 0.08);
  --shadow-lg: 0 20px 40px -15px rgba(37, 99, 235, 0.12);
  --transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  --max-width: 1200px;
}

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

html {
  scroll-behavior: smooth;
  font-family: 'Plus Jakarta Sans', 'Noto Sans SC', system-ui, -apple-system, sans-serif;
  background-color: var(--bg-page);
  color: var(--text-dark);
  line-height: 1.6;
}

body {
  overflow-x: hidden;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Header & Nav */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-light);
  transition: var(--transition);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
}

.brand-logo {
  width: 40px;
  height: 40px;
  object-fit: contain;
  border-radius: var(--radius-sm);
}

.brand-name {
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--primary);
  letter-spacing: -0.5px;
}

.brand-tag {
  font-size: 0.75rem;
  background: var(--primary-light);
  color: var(--primary);
  padding: 2px 8px;
  border-radius: var(--radius-full);
  font-weight: 600;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 2rem;
  list-style: none;
}

.nav-links a {
  text-decoration: none;
  color: var(--text-dark);
  font-weight: 500;
  font-size: 0.95rem;
  transition: var(--transition);
}

.nav-links a:hover {
  color: var(--primary);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 1rem;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.65rem 1.4rem;
  font-size: 0.95rem;
  font-weight: 600;
  border-radius: var(--radius-full);
  text-decoration: none;
  transition: var(--transition);
  cursor: pointer;
  border: none;
}

.btn-primary {
  background: var(--primary);
  color: #ffffff;
  box-shadow: 0 4px 14px var(--primary-glow);
}

.btn-primary:hover {
  background: var(--primary-hover);
  transform: translateY(-1px);
  box-shadow: 0 6px 20px rgba(37, 99, 235, 0.25);
}

.btn-secondary {
  background: #ffffff;
  color: var(--primary);
  border: 1px solid #cbd5e1;
}

.btn-secondary:hover {
  border-color: var(--primary);
  background: var(--primary-light);
}

.btn-recommend {
  background: linear-gradient(135deg, #0284c7, #2563eb);
  color: #ffffff;
  box-shadow: 0 4px 14px rgba(2, 132, 199, 0.25);
}

.btn-recommend:hover {
  filter: brightness(1.08);
  transform: translateY(-1px);
}

.btn-lg {
  padding: 0.85rem 2rem;
  font-size: 1.1rem;
}

/* Hero Section */
.hero {
  position: relative;
  padding: 5rem 1.5rem 4rem;
  background: radial-gradient(circle at 50% 0%, rgba(239, 246, 255, 0.8) 0%, rgba(248, 250, 252, 0) 70%);
  text-align: center;
  overflow: hidden;
}

.hero-container {
  max-width: 900px;
  margin: 0 auto;
}

.pill-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: #ffffff;
  border: 1px solid #bfdbfe;
  padding: 0.4rem 1.1rem;
  border-radius: var(--radius-full);
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--primary);
  box-shadow: var(--shadow-sm);
  margin-bottom: 1.5rem;
}

.pill-badge .tag {
  background: var(--accent-warm);
  color: #fff;
  font-size: 0.72rem;
  padding: 2px 6px;
  border-radius: 4px;
  text-transform: uppercase;
}

.hero-title {
  font-size: 3.2rem;
  font-weight: 900;
  line-height: 1.25;
  letter-spacing: -1px;
  color: var(--text-dark);
  margin-bottom: 1.25rem;
}

.hero-title span {
  color: var(--primary);
}

.hero-subtitle {
  font-size: 1.2rem;
  color: var(--text-muted);
  max-width: 720px;
  margin: 0 auto 2.5rem;
  line-height: 1.7;
}

.hero-ctas {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1.25rem;
  flex-wrap: wrap;
}

/* Stats Ribbon */
.stats-ribbon {
  max-width: var(--max-width);
  margin: 3rem auto 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1.5rem;
  padding: 0 1.5rem;
}

.stat-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  text-align: center;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

.stat-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: var(--border-focus);
}

.stat-icon {
  font-size: 2rem;
  margin-bottom: 0.5rem;
  display: block;
}

.stat-value {
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--text-dark);
}

.stat-label {
  font-size: 0.88rem;
  color: var(--text-muted);
}

/* Section Shared */
.section {
  padding: 5rem 1.5rem;
}

.section-container {
  max-width: var(--max-width);
  margin: 0 auto;
}

.section-header {
  text-align: center;
  max-width: 700px;
  margin: 0 auto 3.5rem;
}

.section-title {
  font-size: 2.2rem;
  font-weight: 800;
  letter-spacing: -0.5px;
  margin-bottom: 0.75rem;
}

.section-desc {
  font-size: 1.05rem;
  color: var(--text-muted);
}

/* Pricing Grid */
.pricing-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(270px, 1fr));
  gap: 2rem;
  align-items: stretch;
}

.price-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 2.25rem 1.75rem;
  position: relative;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

.price-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-lg);
  border-color: var(--primary);
}

.price-card.featured {
  border: 2px solid var(--primary);
  background: linear-gradient(180deg, #ffffff 0%, #f0f7ff 100%);
}

.featured-badge {
  position: absolute;
  top: -14px;
  right: 24px;
  background: var(--accent-warm);
  color: #fff;
  font-size: 0.78rem;
  font-weight: 700;
  padding: 4px 12px;
  border-radius: var(--radius-full);
}

.price-name {
  font-size: 1.3rem;
  font-weight: 800;
  margin-bottom: 0.5rem;
}

.price-desc {
  font-size: 0.88rem;
  color: var(--text-muted);
  margin-bottom: 1.5rem;
  min-height: 40px;
}

.price-amount {
  font-size: 2.5rem;
  font-weight: 900;
  color: var(--primary);
  display: flex;
  align-items: baseline;
  gap: 0.25rem;
  margin-bottom: 1.5rem;
}

.price-unit {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-muted);
}

.price-features {
  list-style: none;
  margin-bottom: 2rem;
  flex-grow: 1;
}

.price-features li {
  font-size: 0.92rem;
  color: var(--text-dark);
  margin-bottom: 0.85rem;
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.price-features li::before {
  content: "✓";
  color: var(--primary);
  font-weight: 900;
}

/* Feature Grid */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 2rem;
}

.feature-box {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 2rem;
  transition: var(--transition);
}

.feature-box:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--border-focus);
}

.feature-icon-wrapper {
  width: 52px;
  height: 52px;
  background: var(--primary-light);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  color: var(--primary);
  margin-bottom: 1.25rem;
}

.feature-title {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.feature-desc {
  font-size: 0.95rem;
  color: var(--text-muted);
  line-height: 1.6;
}

/* Testimonials / User Reviews */
.testimonials-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.75rem;
}

.testimonial-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 1.75rem;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.stars {
  color: #f59e0b;
  font-size: 1.1rem;
  letter-spacing: 2px;
}

.testimonial-text {
  font-size: 0.95rem;
  color: #334155;
  line-height: 1.6;
  font-style: italic;
}

.user-info {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-top: auto;
}

.user-avatar {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-full);
  background: var(--primary-light);
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
}

.user-details h4 {
  font-size: 0.95rem;
  font-weight: 700;
}

.user-details p {
  font-size: 0.8rem;
  color: var(--text-light);
}

/* FAQ Section */
.faq-list {
  max-width: 850px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: var(--transition);
}

.faq-question {
  padding: 1.25rem 1.5rem;
  font-weight: 700;
  font-size: 1.05rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  user-select: none;
}

.faq-question::after {
  content: "+";
  font-size: 1.4rem;
  color: var(--primary);
  transition: var(--transition);
}

.faq-item.active .faq-question::after {
  content: "−";
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  padding: 0 1.5rem;
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.7;
  transition: max-height 0.3s ease, padding 0.3s ease;
}

.faq-item.active .faq-answer {
  max-height: 250px;
  padding: 0 1.5rem 1.25rem;
}

/* Articles Section Grid */
.articles-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 2rem;
}

.article-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  transition: var(--transition);
  text-decoration: none;
  color: inherit;
}

.article-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--border-focus);
}

.article-tag {
  font-size: 0.78rem;
  color: var(--primary);
  font-weight: 700;
  text-transform: uppercase;
  margin-bottom: 0.5rem;
}

.article-card h3 {
  font-size: 1.15rem;
  font-weight: 700;
  line-height: 1.4;
  margin-bottom: 0.75rem;
  color: var(--text-dark);
}

.article-card p {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.6;
  margin-bottom: 1.25rem;
}

.article-readmore {
  margin-top: auto;
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--primary);
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

/* Article Page Layout */
.article-page {
  max-width: 900px;
  margin: 3rem auto 5rem;
  padding: 0 1.5rem;
}

.breadcrumb {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-bottom: 2rem;
}

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

.article-header-meta {
  margin-bottom: 2rem;
  border-bottom: 1px solid var(--border-light);
  padding-bottom: 1.5rem;
}

.article-header-meta h1 {
  font-size: 2.2rem;
  font-weight: 800;
  line-height: 1.3;
  margin-bottom: 1rem;
}

.article-post-info {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  font-size: 0.88rem;
  color: var(--text-light);
}

.article-content {
  font-size: 1.05rem;
  line-height: 1.8;
  color: #334155;
}

.article-content h2 {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-dark);
  margin: 2rem 0 1rem;
}

.article-content h3 {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-dark);
  margin: 1.5rem 0 0.75rem;
}

.article-content p {
  margin-bottom: 1.25rem;
}

.article-content ul, .article-content ol {
  margin: 1rem 0 1.5rem 1.5rem;
}

.article-content li {
  margin-bottom: 0.5rem;
}

.cta-box-article {
  background: linear-gradient(135deg, #eff6ff 0%, #dbeafe 100%);
  border: 1px solid #bfdbfe;
  border-radius: var(--radius-md);
  padding: 2rem;
  text-align: center;
  margin: 3rem 0;
}

.cta-box-article h3 {
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--primary);
  margin-bottom: 0.5rem;
}

.cta-box-article p {
  color: var(--text-muted);
  margin-bottom: 1.25rem;
}

/* Footer Section - Task 2 Compliance */
footer {
  background: #0f172a;
  color: #94a3b8;
  padding: 3.5rem 1.5rem 2rem;
  margin-top: auto;
  border-top: 1px solid #1e293b;
  text-align: center;
}

.footer-container {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.75rem;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
}

.footer-brand img {
  width: 32px;
  height: 32px;
}

.footer-brand span {
  font-size: 1.2rem;
  font-weight: 800;
  color: #ffffff;
}

.footer-copy {
  font-size: 0.88rem;
  color: #64748b;
}

/* Footer PBN Friend Links - Task 2 Strict Requirements */
.footer-friend-links {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1.5rem;
  font-size: 0.82rem;
  color: #64748b;
  border-top: 1px dashed #334155;
  padding-top: 1.25rem;
  width: 100%;
  max-width: 600px;
}

.footer-friend-links span {
  color: #475569;
}

.footer-friend-links a {
  color: #94a3b8;
  text-decoration: none;
  transition: var(--transition);
  font-weight: 500;
}

.footer-friend-links a:hover {
  color: var(--primary-light);
  text-decoration: underline;
}

/* Responsive queries */
@media (max-width: 768px) {
  .nav-links {
    display: none;
  }
  
  .hero-title {
    font-size: 2.2rem;
  }
  
  .hero-subtitle {
    font-size: 1rem;
  }

  .section {
    padding: 3.5rem 1rem;
  }
  
  .pricing-grid {
    grid-template-columns: 1fr;
  }

  .footer-friend-links {
    flex-wrap: wrap;
    gap: 0.75rem;
  }
}