/* --------------------------------------------------------------------------
   Xingyun VPN (星云VPN / 鏄熶簯VPN) - Specification & Receipt Theme Stylesheet
   Color Palette:
   - Clean White: #FFFFFF
   - Espresso Black: #292623
   - Muted Brick: #A96E5B
   - Receipt Gray: #ECEAE6
   -------------------------------------------------------------------------- */

:root {
  --bg-main: #ECEAE6;
  --surface-card: #FFFFFF;
  --text-primary: #292623;
  --text-muted: #5C5650;
  --accent-brick: #A96E5B;
  --border-dark: #292623;
  --border-muted: #D3CEC6;
  --border-dashed: #A96E5B;
  --font-heading: 'Arial Narrow', 'Franklin Gothic Medium', 'Trebuchet MS', system-ui, sans-serif;
  --font-body: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: 'SF Mono', Consolas, 'Liberation Mono', Menlo, Courier, monospace;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  background-color: var(--bg-main);
  color: var(--text-primary);
  font-family: var(--font-body);
}

body {
  font-size: 17px;
  line-height: 1.65;
  color: var(--text-primary);
  background-color: var(--bg-main);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Typography */
h1, h2, h3, h4, .font-heading {
  font-family: var(--font-heading);
  color: var(--text-primary);
  font-weight: 700;
  letter-spacing: -0.01em;
  line-height: 1.18;
}

h1 {
  font-size: clamp(33px, 5vw, 48px);
  text-transform: uppercase;
  margin-bottom: 0.5em;
}

h2 {
  font-size: clamp(24px, 3.5vw, 34px);
  margin-bottom: 0.6em;
  border-bottom: 2px solid var(--border-dark);
  padding-bottom: 0.3em;
}

h3 {
  font-size: clamp(18px, 2.5vw, 22px);
  margin-bottom: 0.4em;
}

p {
  margin-bottom: 1em;
  color: var(--text-primary);
}

p:last-child {
  margin-bottom: 0;
}

a {
  color: var(--text-primary);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
  transition: color 0.2s ease, text-decoration-color 0.2s ease;
}

a:hover, a:focus-visible {
  color: var(--accent-brick);
  text-decoration-color: var(--accent-brick);
}

.mono-tag {
  font-family: var(--font-mono);
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent-brick);
  display: inline-block;
  background-color: rgba(169, 110, 91, 0.1);
  padding: 2px 8px;
  border: 1px dashed var(--accent-brick);
  margin-bottom: 8px;
}

.disclaimer-box {
  background-color: #F4F2EE;
  border-left: 3px solid var(--accent-brick);
  padding: 12px 16px;
  font-size: 13px;
  color: var(--text-muted);
  font-family: var(--font-mono);
  margin-top: 16px;
  margin-bottom: 16px;
  line-height: 1.5;
}

/* Container & Layout Grid */
.container {
  width: 100%;
  max-width: 1240px;
  margin: 0 auto;
  padding: 0 20px;
}

section {
  padding: 50px 0;
  border-bottom: 1px solid var(--border-muted);
}

@media (min-width: 768px) {
  section {
    padding: 70px 0;
  }
}

/* Buttons & CTAs */
.btn-cta {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background-color: var(--text-primary);
  color: #FFFFFF;
  font-family: var(--font-mono);
  font-size: 15px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 14px 28px;
  border: 2px solid var(--text-primary);
  text-decoration: none;
  cursor: pointer;
  transition: border-color 0.2s ease, outline-offset 0.2s ease, background-color 0.2s ease, color 0.2s ease;
}

.btn-cta:hover, .btn-cta:focus-visible {
  background-color: var(--accent-brick);
  border-color: var(--accent-brick);
  color: #FFFFFF;
  outline: 1px solid var(--accent-brick);
  outline-offset: 3px;
  text-decoration: none;
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background-color: transparent;
  color: var(--text-primary);
  font-family: var(--font-mono);
  font-size: 14px;
  font-weight: 600;
  padding: 12px 22px;
  border: 1px solid var(--border-dark);
  text-decoration: none;
  transition: border-color 0.2s ease, color 0.2s ease;
}

.btn-secondary:hover, .btn-secondary:focus-visible {
  border-color: var(--accent-brick);
  color: var(--accent-brick);
  text-decoration: none;
}

/* Navigation Header */
.site-header {
  background-color: var(--surface-card);
  border-bottom: 2px solid var(--border-dark);
  position: sticky;
  top: 0;
  z-index: 1000;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 70px;
}

.brand-logo {
  font-family: var(--font-heading);
  font-size: 24px;
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 8px;
}

.brand-logo .brand-badge {
  font-family: var(--font-mono);
  font-size: 11px;
  background: var(--text-primary);
  color: #FFFFFF;
  padding: 2px 6px;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 24px;
  list-style: none;
}

.nav-link {
  font-family: var(--font-mono);
  font-size: 14px;
  text-transform: uppercase;
  color: var(--text-primary);
  text-decoration: none;
  padding: 6px 0;
  position: relative;
}

.nav-link:hover, .nav-link:focus-visible {
  color: var(--accent-brick);
  text-decoration: none;
}

.mobile-menu-toggle {
  display: none;
  background: none;
  border: 1px solid var(--border-dark);
  padding: 8px 12px;
  font-family: var(--font-mono);
  font-size: 14px;
  cursor: pointer;
  color: var(--text-primary);
}

@media (max-width: 900px) {
  .mobile-menu-toggle {
    display: block;
  }
  .nav-menu {
    display: none;
    position: absolute;
    top: 70px;
    left: 0;
    width: 100%;
    background-color: var(--surface-card);
    border-bottom: 2px solid var(--border-dark);
    flex-direction: column;
    align-items: flex-start;
    padding: 20px;
    gap: 16px;
    box-shadow: 0 10px 20px rgba(0,0,0,0.05);
  }
  .nav-menu.active {
    display: flex;
  }
}

/* Specification Slips & Cards System */
.spec-card {
  background-color: var(--surface-card);
  border: 1px solid var(--border-dark);
  padding: 24px;
  position: relative;
  transition: border-color 0.25s ease, outline-offset 0.25s ease;
}

.spec-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background-color: var(--border-dark);
}

.spec-card:hover {
  border-color: var(--accent-brick);
  outline: 1px solid var(--accent-brick);
  outline-offset: 3px;
}

.spec-slip-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px dashed var(--border-muted);
  padding-bottom: 12px;
  margin-bottom: 16px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--text-muted);
}

/* Hero Section */
.hero-section {
  padding: 60px 0;
  background-color: var(--bg-main);
}

.hero-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 40px;
  align-items: center;
}

@media (min-width: 992px) {
  .hero-grid {
    grid-template-columns: 1.1fr 0.9fr;
    gap: 50px;
  }
}

.hero-content .product-summary {
  font-size: 18px;
  color: var(--text-muted);
  margin-bottom: 24px;
  max-width: 600px;
}

.hero-actions {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 24px;
}

/* Network Dashboard / Stacked Slips */
.dashboard-slip-stack {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.slip-item {
  background-color: var(--surface-card);
  border: 1px solid var(--border-dark);
  padding: 16px 20px;
  position: relative;
}

.slip-item-header {
  display: flex;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: 12px;
  border-bottom: 1px dashed var(--border-muted);
  padding-bottom: 8px;
  margin-bottom: 12px;
}

.route-lines {
  display: flex;
  flex-direction: column;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 13px;
}

.route-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 4px 8px;
  background: var(--bg-main);
  border-left: 2px solid var(--accent-brick);
}

.route-status {
  color: var(--accent-brick);
  font-weight: 600;
}

/* Benefits Broad Rows */
.benefit-row {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
  background: var(--surface-card);
  border: 1px solid var(--border-dark);
  padding: 32px;
  margin-bottom: 24px;
  align-items: center;
  transition: border-color 0.25s ease, outline-offset 0.25s ease;
}

.benefit-row:hover {
  border-color: var(--accent-brick);
  outline: 1px solid var(--accent-brick);
  outline-offset: 3px;
}

@media (min-width: 768px) {
  .benefit-row {
    grid-template-columns: 120px 1fr;
    gap: 32px;
  }
}

.benefit-number {
  font-family: var(--font-heading);
  font-size: 64px;
  font-weight: 700;
  color: var(--accent-brick);
  line-height: 1;
}

/* Location Manifest (Worldwide Nodes) */
.node-manifest-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
}

@media (min-width: 600px) {
  .node-manifest-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 992px) {
  .node-manifest-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

.node-card {
  background-color: var(--surface-card);
  border: 1px solid var(--border-dark);
  padding: 20px;
  font-family: var(--font-mono);
}

.node-card-title {
  font-family: var(--font-heading);
  font-size: 20px;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.node-card-details {
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.6;
}

/* AI / Streaming Scenarios Paired Layout */
.scenario-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
}

@media (min-width: 768px) {
  .scenario-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

.scenario-card {
  background: var(--surface-card);
  border: 1px solid var(--border-dark);
  padding: 24px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.scenario-pair {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-top: 16px;
  padding-top: 16px;
  border-top: 1px dashed var(--border-muted);
}

.scenario-box {
  background: var(--bg-main);
  padding: 12px;
  border: 1px solid var(--border-muted);
  font-size: 13px;
}

.scenario-box-title {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--accent-brick);
  margin-bottom: 4px;
  text-transform: uppercase;
}

/* Pricing Invoice Section */
.pricing-invoice-container {
  background-color: var(--surface-card);
  border: 2px solid var(--border-dark);
  padding: 32px;
  max-width: 1000px;
  margin: 0 auto;
}

.invoice-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  border-bottom: 2px dashed var(--border-dark);
  padding-bottom: 20px;
  margin-bottom: 24px;
  flex-wrap: wrap;
  gap: 16px;
}

.pricing-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
  margin-bottom: 24px;
}

@media (min-width: 768px) {
  .pricing-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

.pricing-card {
  border: 1px solid var(--border-dark);
  padding: 24px;
  background: var(--bg-main);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  position: relative;
}

.pricing-card.featured {
  background: var(--surface-card);
  border: 2px solid var(--accent-brick);
}

.pricing-price {
  font-family: var(--font-heading);
  font-size: 36px;
  color: var(--text-primary);
  margin: 12px 0;
}

.pricing-features {
  list-style: none;
  font-size: 14px;
  margin: 16px 0;
  line-height: 1.8;
}

.pricing-features li {
  padding-left: 16px;
  position: relative;
}

.pricing-features li::before {
  content: "•";
  color: var(--accent-brick);
  position: absolute;
  left: 0;
}

/* Nine SEO Cards Grid */
.seo-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
}

@media (min-width: 600px) {
  .seo-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 992px) {
  .seo-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

/* Articles Grid (3 Desktop / 2 Tablet / 1 Mobile) */
.articles-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
}

@media (min-width: 600px) {
  .articles-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .articles-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

.article-slip-card {
  background: var(--surface-card);
  border: 1px solid var(--border-dark);
  padding: 24px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: border-color 0.25s ease, outline-offset 0.25s ease;
}

.article-slip-card:hover {
  border-color: var(--accent-brick);
  outline: 1px solid var(--accent-brick);
  outline-offset: 3px;
}

.article-slip-number {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--accent-brick);
  border-bottom: 1px dashed var(--border-muted);
  padding-bottom: 8px;
  margin-bottom: 12px;
}

.article-slip-title {
  font-family: var(--font-heading);
  font-size: 20px;
  margin-bottom: 10px;
  line-height: 1.3;
}

.article-slip-desc {
  font-size: 14px;
  color: var(--text-muted);
  margin-bottom: 16px;
  flex-grow: 1;
}

/* Testimonials Grid */
.testimonials-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
}

@media (min-width: 768px) {
  .testimonials-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

.testimonial-card {
  background: var(--surface-card);
  border: 1px solid var(--border-dark);
  padding: 20px;
  font-style: normal;
}

.testimonial-quote {
  font-size: 15px;
  margin-bottom: 12px;
  color: var(--text-primary);
}

.testimonial-author {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--accent-brick);
}

/* FAQ Accordion */
.faq-accordion {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.faq-item {
  background: var(--surface-card);
  border: 1px solid var(--border-dark);
}

.faq-item details {
  padding: 16px 20px;
}

.faq-item summary {
  font-family: var(--font-heading);
  font-size: 18px;
  font-weight: 700;
  cursor: pointer;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-item summary::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: 20px;
  color: var(--accent-brick);
}

.faq-item details[open] summary::after {
  content: "−";
}

.faq-answer {
  margin-top: 12px;
  padding-top: 12px;
  border-top: 1px dashed var(--border-muted);
  font-size: 15px;
  color: var(--text-primary);
}

/* Breadcrumbs */
.breadcrumb {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--text-muted);
  margin-bottom: 24px;
}

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

.breadcrumb a:hover {
  color: var(--accent-brick);
  text-decoration: underline;
}

.breadcrumb-separator {
  margin: 0 8px;
}

/* Footer */
.site-footer {
  background: var(--surface-card);
  border-top: 2px solid var(--border-dark);
  padding: 50px 0 30px;
  margin-top: auto;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 32px;
  margin-bottom: 40px;
}

@media (min-width: 768px) {
  .footer-grid {
    grid-template-columns: 2fr 1fr 1fr;
  }
}

.footer-col-title {
  font-family: var(--font-heading);
  font-size: 18px;
  margin-bottom: 16px;
  text-transform: uppercase;
}

.footer-links {
  list-style: none;
  font-family: var(--font-mono);
  font-size: 13px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.footer-bottom {
  border-top: 1px dashed var(--border-muted);
  padding-top: 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--text-muted);
}

/* Reduced Motion Support */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation: none !important;
    transition: none !important;
  }
}