/* Qingyunti (青云梯) Master Stylesheet - White Theme Edition */
:root {
  --primary: #0ea5e9;
  --primary-hover: #0284c7;
  --primary-light: rgba(14, 165, 233, 0.1);
  --accent: #06b6d4;
  --accent-glow: rgba(6, 182, 212, 0.2);
  --bg-white: #ffffff;
  --bg-subtle: #f8fafc;
  --bg-card: #ffffff;
  --text-main: #0f172a;
  --text-muted: #334155;
  --text-dim: #64748b;
  --border-color: #e2e8f0;
  --border-highlight: rgba(14, 165, 233, 0.4);
  --shadow-sm: 0 2px 8px rgba(15, 23, 42, 0.04);
  --shadow-md: 0 4px 20px rgba(15, 23, 42, 0.06);
  --shadow-lg: 0 10px 30px rgba(15, 23, 42, 0.1);
  --radius-lg: 16px;
  --radius-md: 12px;
  --radius-sm: 8px;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --max-width: 1240px;
}

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

html {
  scroll-behavior: smooth;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background-color: var(--bg-white);
  color: var(--text-main);
  line-height: 1.6;
}

body {
  overflow-x: hidden;
  background-color: #ffffff;
  background-image: 
    radial-gradient(circle at 10% 20%, rgba(14, 165, 233, 0.05) 0%, transparent 40%),
    radial-gradient(circle at 90% 60%, rgba(6, 182, 212, 0.05) 0%, transparent 40%);
  min-height: 100vh;
}

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

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

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Header & Navigation */
header.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-color);
  padding: 0.9rem 0;
  box-shadow: var(--shadow-sm);
}

.nav-wrapper {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text-main);
}

.brand img.logo-img {
  width: 38px;
  height: 38px;
  border-radius: 8px;
  object-fit: cover;
  box-shadow: 0 2px 8px rgba(14, 165, 233, 0.2);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.75rem;
  list-style: none;
}

.nav-links a {
  color: var(--text-muted);
  font-size: 0.95rem;
  font-weight: 600;
}

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

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

.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-md);
  cursor: pointer;
  transition: var(--transition);
  border: none;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: #ffffff;
  box-shadow: 0 4px 15px rgba(14, 165, 233, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(14, 165, 233, 0.45);
  color: #ffffff;
}

.btn-recommend {
  background: rgba(14, 165, 233, 0.1);
  color: var(--primary);
  border: 1px solid rgba(14, 165, 233, 0.3);
}

.btn-recommend:hover {
  background: var(--primary);
  color: #ffffff;
}

.btn-secondary {
  background: #f1f5f9;
  color: var(--text-main);
  border: 1px solid var(--border-color);
}

.btn-secondary:hover {
  background: #e2e8f0;
  border-color: #cbd5e1;
}

/* Hero Section with Side Illustration Layout */
.hero {
  padding: 4rem 0 3.5rem;
  position: relative;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  align-items: center;
  gap: 3rem;
}

.hero-text {
  text-align: left;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.35rem 1rem;
  background: rgba(14, 165, 233, 0.08);
  border: 1px solid rgba(14, 165, 233, 0.25);
  border-radius: 50px;
  color: var(--primary);
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: 1.5rem;
}

.hero h1 {
  font-size: 3.25rem;
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 1.25rem;
  color: var(--text-main);
}

.hero p.subtitle {
  font-size: 1.15rem;
  color: var(--text-muted);
  margin-bottom: 2.25rem;
  line-height: 1.7;
}

.hero-cta {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  margin-bottom: 2.5rem;
  flex-wrap: wrap;
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
}

.stat-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  padding: 1.25rem;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
}

.stat-card .num {
  font-size: 1.8rem;
  font-weight: 800;
  color: var(--primary);
  display: block;
}

.stat-card .label {
  font-size: 0.85rem;
  color: var(--text-dim);
  margin-top: 0.2rem;
}

/* Side Margin Cyan Ladder & Cloud Artwork */
.hero-illustration {
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
}

.hero-illustration img.cloud-ladder-img {
  width: 100%;
  max-width: 540px;
  height: auto;
  border-radius: var(--radius-lg);
  filter: drop-shadow(0 15px 35px rgba(14, 165, 233, 0.15));
  animation: floatLadder 4s ease-in-out infinite;
}

@keyframes floatLadder {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-10px); }
}

/* Floating side decoration on wide screens */
.side-margin-artwork {
  position: fixed;
  right: 20px;
  top: 180px;
  z-index: 10;
  width: 180px;
  pointer-events: none;
  opacity: 0.85;
}

@media (max-width: 1400px) {
  .side-margin-artwork { display: none; }
}

/* Feature Grid */
.features-section {
  padding: 4.5rem 0;
  background: var(--bg-subtle);
  border-top: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
}

.section-title {
  text-align: center;
  margin-bottom: 3rem;
}

.section-title h2 {
  font-size: 2.25rem;
  font-weight: 800;
  margin-bottom: 0.75rem;
  color: var(--text-main);
}

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

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(270px, 1fr));
  gap: 1.5rem;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2rem;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

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

.feature-icon {
  width: 52px;
  height: 52px;
  border-radius: var(--radius-md);
  background: var(--primary-light);
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: 1.25rem;
}

.feature-card h3 {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
  color: var(--text-main);
}

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

/* Pricing Section */
.pricing-section {
  padding: 4.5rem 0;
  background: #ffffff;
}

.pricing-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.5rem;
  margin-top: 2rem;
}

.pricing-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2rem 1.5rem;
  display: flex;
  flex-direction: column;
  position: relative;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

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

.pricing-card.popular {
  border-color: var(--primary);
  box-shadow: var(--shadow-lg);
  background: linear-gradient(180deg, rgba(14, 165, 233, 0.04) 0%, #ffffff 100%);
}

.pricing-badge {
  position: absolute;
  top: -12px;
  right: 20px;
  background: var(--primary);
  color: #fff;
  font-size: 0.75rem;
  font-weight: 700;
  padding: 0.2rem 0.75rem;
  border-radius: 20px;
  text-transform: uppercase;
}

.plan-name {
  font-size: 1.25rem;
  font-weight: 800;
  margin-bottom: 0.5rem;
  color: var(--text-main);
}

.plan-traffic {
  color: var(--primary);
  font-weight: 700;
  font-size: 1rem;
  margin-bottom: 1rem;
}

.price-box {
  margin-bottom: 1.5rem;
}

.price-box .price {
  font-size: 2.25rem;
  font-weight: 800;
  color: var(--text-main);
}

.price-box .period {
  color: var(--text-dim);
  font-size: 0.85rem;
}

.plan-details {
  list-style: none;
  margin-bottom: 1.5rem;
  flex-grow: 1;
}

.plan-details li {
  font-size: 0.875rem;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.plan-details li::before {
  content: "✓";
  color: var(--primary);
  font-weight: bold;
}

/* Articles Section */
.articles-section {
  padding: 4.5rem 0;
  background: var(--bg-subtle);
  border-top: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
}

.articles-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(330px, 1fr));
  gap: 1.75rem;
}

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

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

.article-tag {
  align-self: flex-start;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--primary);
  background: var(--primary-light);
  padding: 0.25rem 0.75rem;
  border-radius: 20px;
  margin-bottom: 1rem;
}

.article-card h3 {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
  line-height: 1.4;
}

.article-card h3 a {
  color: var(--text-main);
}

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

.article-excerpt {
  color: var(--text-muted);
  font-size: 0.9rem;
  line-height: 1.6;
  margin-bottom: 1.25rem;
  flex-grow: 1;
}

.article-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-top: 1px solid var(--border-color);
  padding-top: 1rem;
  font-size: 0.85rem;
  color: var(--text-dim);
}

/* Reviews Section */
.reviews-section {
  padding: 4.5rem 0;
  background: #ffffff;
}

.reviews-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.5rem;
}

.review-card {
  background: var(--bg-subtle);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  box-shadow: var(--shadow-sm);
}

.review-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1rem;
}

.avatar-circle {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: #fff;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
}

.user-info .name {
  font-weight: 700;
  color: var(--text-main);
  font-size: 1rem;
}

.user-info .role {
  font-size: 0.8rem;
  color: var(--text-dim);
}

.stars {
  color: #f59e0b;
  margin-bottom: 0.75rem;
  font-size: 0.9rem;
}

.review-text {
  color: var(--text-muted);
  font-size: 0.925rem;
  line-height: 1.6;
}

/* FAQ Section */
.faq-section {
  padding: 4.5rem 0;
  background: var(--bg-subtle);
  border-top: 1px solid var(--border-color);
}

.faq-wrapper {
  max-width: 850px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.faq-item {
  background: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

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

.faq-question::after {
  content: "+";
  font-size: 1.4rem;
  color: var(--primary);
  transition: transform 0.3s ease;
}

.faq-item.active .faq-question::after {
  transform: rotate(455deg);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.35s ease-out, padding 0.35s ease;
  padding: 0 1.5rem;
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.7;
}

.faq-item.active .faq-answer {
  max-height: 300px;
  padding: 0 1.5rem 1.25rem;
}

/* Footer Section - PBN Precise Weight Fluid Requirement */
footer {
  background: #f8fafc;
  border-top: 1px solid var(--border-color);
  padding: 3rem 0 2rem;
  text-align: center;
  color: var(--text-dim);
  font-size: 0.875rem;
}

.footer-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.25rem;
}

.footer-links-pbn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1.5rem;
  font-size: 0.8rem;
  color: #64748b;
  margin-top: 0.5rem;
}

.footer-links-pbn span.label {
  color: #64748b;
}

.footer-links-pbn a {
  color: #64748b;
  text-decoration: none;
  font-size: 0.8rem;
  transition: color 0.2s ease;
}

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

/* Article Page Layout Styles */
.article-header-nav {
  margin-bottom: 2rem;
}

.breadcrumb {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.875rem;
  color: var(--text-dim);
  margin-bottom: 1.5rem;
}

.article-content-container {
  max-width: 860px;
  margin: 3rem auto;
  background: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 3rem;
  box-shadow: var(--shadow-sm);
}

.article-main-title {
  font-size: 2.25rem;
  font-weight: 800;
  line-height: 1.3;
  margin-bottom: 1rem;
  color: var(--text-main);
}

.article-meta {
  display: flex;
  gap: 1.5rem;
  font-size: 0.875rem;
  color: var(--text-dim);
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 1.5rem;
  margin-bottom: 2rem;
}

.article-body h2 {
  font-size: 1.5rem;
  font-weight: 800;
  margin: 2rem 0 1rem;
  color: var(--text-main);
  border-left: 4px solid var(--primary);
  padding-left: 0.75rem;
}

.article-body h3 {
  font-size: 1.2rem;
  font-weight: 700;
  margin: 1.5rem 0 0.75rem;
  color: #1e293b;
}

.article-body p {
  color: var(--text-muted);
  margin-bottom: 1.25rem;
  font-size: 1.05rem;
  line-height: 1.8;
}

.article-body ul, .article-body ol {
  margin: 1rem 0 1.5rem 1.5rem;
  color: var(--text-muted);
}

.article-body li {
  margin-bottom: 0.5rem;
  line-height: 1.7;
}

.cta-box-in-article {
  background: linear-gradient(135deg, rgba(14, 165, 233, 0.08), rgba(6, 182, 212, 0.08));
  border: 1px solid var(--border-highlight);
  border-radius: var(--radius-md);
  padding: 2rem;
  text-align: center;
  margin: 2.5rem 0;
}

.cta-box-in-article h3 {
  margin-top: 0;
  color: var(--text-main);
}

.cta-box-in-article p {
  margin-bottom: 1.25rem;
}

/* Responsive Media Queries */
@media (max-width: 992px) {
  .hero-grid { grid-template-columns: 1fr; text-align: center; }
  .hero-text { text-align: center; }
  .hero-cta { justify-content: center; }
  .hero h1 { font-size: 2.35rem; }
  .article-content-container { padding: 1.75rem; }
  .nav-links { display: none; }
}