/* ==========================================================================
   NaNoCloud - Modern Minimalist Style Sheet
   Zero-framework, Native CSS, Ultra-fast Loading & Responsive
   ========================================================================== */

:root {
  --bg-primary: #060913;
  --bg-secondary: #0a101d;
  --bg-card: rgba(10, 16, 29, 0.75);
  --bg-card-hover: rgba(15, 23, 42, 0.9);
  --border-color: rgba(163, 230, 53, 0.18);
  --border-glow: rgba(163, 230, 53, 0.45);
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #94a3b8;
  --accent-blue: #A3E635;
  --accent-cyan: #A3E635;
  --accent-purple: #BEF264;
  --accent-gradient: linear-gradient(135deg, #A3E635 0%, #BEF264 100%);
  --accent-gradient-hover: linear-gradient(135deg, #84cc16 0%, #a3e635 100%);
  --accent-glow: 0 0 25px rgba(163, 230, 53, 0.35);
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --radius-full: 6px;
  --max-width: 1240px;
  --transition: all 0.22s cubic-bezier(0.16, 1, 0.3, 1);
}

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

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

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
  background: radial-gradient(circle at 50% 0%, #172554 0%, #0a0e17 60%);
  background-attachment: fixed;
}

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

.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

/* Anchor Offset for Fixed/Sticky Header */
section[id], [id] {
  scroll-margin-top: 84px;
}

/* Global Keyboard Focus Visible */
:focus-visible {
  outline: 2px solid var(--accent-cyan);
  outline-offset: 3px;
}

.faq-item summary:focus-visible {
  outline: 2px solid var(--accent-cyan);
  outline-offset: -2px;
}

/* ==========================================================================
   Header & Navigation
   ========================================================================== */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(10, 14, 23, 0.85);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-color);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.45rem;
  font-weight: 800;
  letter-spacing: -0.5px;
  color: #ffffff;
}

.brand-icon {
  width: 32px;
  height: 32px;
  color: var(--accent-cyan);
}

.brand-text span {
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 28px;
  list-style: none;
}

.nav-link {
  font-size: 0.95rem;
  color: var(--text-secondary);
  font-weight: 500;
}

.nav-link:hover {
  color: #ffffff;
}

/* Buttons & CTA Specification */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-weight: 600;
  font-size: 0.95rem;
  padding: 10px 22px;
  border-radius: var(--radius-full);
  cursor: pointer;
  border: 1px solid transparent;
  transition: var(--transition);
  min-height: 44px;
  white-space: nowrap;
}

.btn-primary {
  background: var(--accent-gradient);
  color: #060913;
  box-shadow: var(--accent-glow);
  font-weight: 700;
}

.btn-primary:hover {
  background: var(--accent-gradient-hover);
  transform: translateY(-2px);
  box-shadow: 0 0 30px rgba(163, 230, 53, 0.6);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-primary);
  border-color: var(--border-color);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.2);
}

.btn-lg {
  padding: 14px 34px;
  font-size: 1.05rem;
  min-height: 52px;
}

.btn-block {
  width: 100%;
}

/* ==========================================================================
   Hero Section (Main Visual Area)
   ========================================================================== */
.hero {
  padding: 90px 0 60px;
  text-align: center;
  position: relative;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  background: rgba(59, 130, 246, 0.12);
  border: 1px solid rgba(59, 130, 246, 0.3);
  border-radius: var(--radius-full);
  color: var(--accent-cyan);
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 24px;
}

.hero-title {
  font-size: 3.2rem;
  font-weight: 850;
  letter-spacing: -1.5px;
  line-height: 1.2;
  margin-bottom: 20px;
  max-width: 900px;
  margin-left: auto;
  margin-right: auto;
}

.hero-title .highlight {
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-subtitle {
  font-size: 1.2rem;
  color: var(--text-secondary);
  max-width: 760px;
  margin: 0 auto 36px;
  font-weight: 400;
  line-height: 1.7;
}

.hero-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  margin-bottom: 48px;
}

.hero-highlights {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 32px;
  padding: 20px 0;
  border-top: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
  max-width: 860px;
  margin: 0 auto;
}

.highlight-item {
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.highlight-item svg {
  color: #10b981;
  width: 18px;
  height: 18px;
}

/* ==========================================================================
   Section Common Styles
   ========================================================================== */
.section {
  padding: 90px 0;
}

.section-header {
  text-align: center;
  max-width: 680px;
  margin: 0 auto 54px;
}

.section-tag {
  text-transform: uppercase;
  color: var(--accent-cyan);
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 1.5px;
  margin-bottom: 10px;
  display: inline-block;
}

.section-title {
  font-size: 2.2rem;
  font-weight: 800;
  letter-spacing: -0.8px;
  margin-bottom: 14px;
}

.section-desc {
  font-size: 1rem;
  color: var(--text-secondary);
}

/* ==========================================================================
   Core Advantages (3 Graphic Cards)
   ========================================================================== */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 36px 30px;
  transition: var(--transition);
  display: flex;
  flex-direction: column;
  position: relative;
  overflow: hidden;
  backdrop-filter: blur(8px);
}

.feature-card:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-glow);
  transform: translateY(-4px);
  box-shadow: 0 12px 30px rgba(0, 0, 0, 0.4);
}

.feature-icon-wrapper {
  width: 58px;
  height: 58px;
  border-radius: var(--radius-md);
  background: rgba(59, 130, 246, 0.15);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--accent-cyan);
  margin-bottom: 24px;
  border: 1px solid rgba(59, 130, 246, 0.25);
}

.feature-title {
  font-size: 1.35rem;
  font-weight: 700;
  margin-bottom: 12px;
}

.feature-desc {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.7;
  margin-bottom: 20px;
}

.feature-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: auto;
}

.feature-pill {
  font-size: 0.78rem;
  padding: 4px 10px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: var(--radius-full);
  color: var(--text-secondary);
}

/* ==========================================================================
   Streaming & AI Support Section
   ========================================================================== */
.support-wrapper {
  background: linear-gradient(180deg, rgba(17, 24, 39, 0.8) 0%, rgba(10, 14, 23, 0.9) 100%);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 48px;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  align-items: center;
}

.support-content h3 {
  font-size: 1.85rem;
  font-weight: 800;
  margin-bottom: 16px;
  line-height: 1.3;
}

.support-content p {
  color: var(--text-secondary);
  font-size: 1rem;
  margin-bottom: 24px;
  line-height: 1.7;
}

.support-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 14px;
  margin-bottom: 30px;
}

.support-list li {
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--text-primary);
  font-size: 0.95rem;
}

.support-list svg {
  color: var(--accent-cyan);
  width: 20px;
  height: 20px;
  flex-shrink: 0;
}

.support-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
}

.support-item-box {
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 20px;
  transition: var(--transition);
}

.support-item-box:hover {
  border-color: var(--accent-blue);
  background: rgba(59, 130, 246, 0.06);
}

.support-item-box .item-header {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 8px;
  font-weight: 700;
  font-size: 1.05rem;
}

.support-item-box p {
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin: 0;
}

/* ==========================================================================
   Pricing Section
   ========================================================================== */
.pricing-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
  align-items: stretch;
}

.pricing-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 40px 32px;
  display: flex;
  flex-direction: column;
  position: relative;
  transition: var(--transition);
}

.pricing-card:hover {
  transform: translateY(-4px);
  border-color: rgba(255, 255, 255, 0.18);
}

.pricing-card.featured {
  background: linear-gradient(180deg, rgba(29, 44, 76, 0.85) 0%, rgba(17, 24, 39, 0.95) 100%);
  border: 2px solid var(--accent-blue);
  box-shadow: 0 10px 40px rgba(59, 130, 246, 0.2);
  transform: scale(1.03);
}

.pricing-card.featured:hover {
  transform: scale(1.03) translateY(-4px);
}

.pricing-badge {
  position: absolute;
  top: -14px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--accent-gradient);
  color: #ffffff;
  font-size: 0.78rem;
  font-weight: 700;
  padding: 4px 16px;
  border-radius: var(--radius-full);
  text-transform: uppercase;
  letter-spacing: 1px;
}

.plan-name {
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 6px;
}

.plan-desc {
  color: var(--text-secondary);
  font-size: 0.88rem;
  margin-bottom: 24px;
}

.plan-price {
  display: flex;
  align-items: baseline;
  gap: 4px;
  margin-bottom: 28px;
}

.plan-price .currency {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--accent-cyan);
}

.plan-price .amount {
  font-size: 2.8rem;
  font-weight: 850;
  letter-spacing: -1px;
}

.plan-price .period {
  color: var(--text-muted);
  font-size: 0.9rem;
}

.plan-features {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 14px;
  margin-bottom: 34px;
  flex-grow: 1;
}

.plan-features li {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 0.92rem;
  color: var(--text-secondary);
}

.plan-features li.active {
  color: var(--text-primary);
}

.plan-features svg {
  width: 17px;
  height: 17px;
  color: #10b981;
  flex-shrink: 0;
}

/* ==========================================================================
   Testimonials (User Reviews)
   ========================================================================== */
.testimonials-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}

.testimonial-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 32px;
  display: flex;
  flex-direction: column;
  transition: var(--transition);
}

.testimonial-card:hover {
  border-color: rgba(255, 255, 255, 0.15);
  background: var(--bg-card-hover);
}

.stars {
  display: flex;
  gap: 4px;
  margin-bottom: 16px;
  color: #f59e0b;
}

.testimonial-quote {
  font-size: 0.95rem;
  line-height: 1.7;
  color: var(--text-secondary);
  margin-bottom: 24px;
  flex-grow: 1;
  font-style: italic;
}

.testimonial-user {
  display: flex;
  align-items: center;
  gap: 14px;
  border-top: 1px solid var(--border-color);
  padding-top: 18px;
}

.user-avatar {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--accent-gradient);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1rem;
  color: #fff;
  flex-shrink: 0;
}

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

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

/* ==========================================================================
   FAQ Section (6 Items)
   ========================================================================== */
.faq-grid {
  max-width: 840px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

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

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

.faq-item details {
  width: 100%;
}

.faq-item summary {
  padding: 22px 24px;
  font-size: 1.05rem;
  font-weight: 600;
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  user-select: none;
  outline: none;
}

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

.faq-icon {
  width: 20px;
  height: 20px;
  color: var(--accent-cyan);
  transition: transform 0.25s ease;
  flex-shrink: 0;
}

.faq-item details[open] .faq-icon {
  transform: rotate(180deg);
}

.faq-content {
  padding: 0 24px 22px;
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.75;
  border-top: 1px solid rgba(255, 255, 255, 0.04);
  padding-top: 16px;
}

/* ==========================================================================
   Bottom CTA Banner
   ========================================================================== */
.cta-banner {
  background: linear-gradient(135deg, rgba(30, 58, 138, 0.6) 0%, rgba(15, 23, 42, 0.8) 100%);
  border: 1px solid rgba(59, 130, 246, 0.3);
  border-radius: var(--radius-lg);
  padding: 60px 40px;
  text-align: center;
  margin: 60px 0 30px;
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.5);
}

.cta-banner h2 {
  font-size: 2.3rem;
  font-weight: 800;
  margin-bottom: 14px;
}

.cta-banner p {
  font-size: 1.1rem;
  color: var(--text-secondary);
  margin-bottom: 30px;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

/* ==========================================================================
   Footer (Strictly 4 Links)
   ========================================================================== */
.footer {
  border-top: 1px solid var(--border-color);
  background: #070a10;
  padding: 50px 0 36px;
  margin-top: auto;
}

.footer-nav {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 36px;
  list-style: none;
  margin-bottom: 28px;
  flex-wrap: wrap;
}

.footer-link {
  font-size: 0.98rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: var(--transition);
  position: relative;
}

.footer-link:hover {
  color: var(--accent-cyan);
}

.footer-bottom {
  text-align: center;
  font-size: 0.85rem;
  color: var(--text-muted);
  border-top: 1px solid rgba(255, 255, 255, 0.04);
  padding-top: 24px;
}

/* ==========================================================================
   Static Sub-Page Layout (About, Terms, Privacy, Sitemap)
   ========================================================================== */
.page-container {
  max-width: 860px;
  margin: 40px auto 80px;
  padding: 0 24px;
}

.page-header {
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 28px;
  margin-bottom: 40px;
}

.page-title {
  font-size: 2.4rem;
  font-weight: 850;
  letter-spacing: -1px;
  margin-bottom: 10px;
}

.page-meta {
  color: var(--text-muted);
  font-size: 0.9rem;
}

.page-body {
  color: var(--text-secondary);
  font-size: 1rem;
  line-height: 1.85;
}

.page-body h2 {
  color: var(--text-primary);
  font-size: 1.45rem;
  font-weight: 700;
  margin: 36px 0 14px;
}

.page-body h3 {
  color: var(--text-primary);
  font-size: 1.15rem;
  font-weight: 600;
  margin: 22px 0 10px;
}

.page-body p {
  margin-bottom: 18px;
}

.page-body ul {
  padding-left: 24px;
  margin-bottom: 24px;
}

.page-body li {
  margin-bottom: 8px;
}

.sitemap-group {
  margin-bottom: 32px;
}

.sitemap-links {
  list-style: none;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 14px;
  margin-top: 14px;
}

.sitemap-links a {
  display: block;
  padding: 12px 18px;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-weight: 500;
}

/* Article FAQ & Internal Linking Matrix */
.article-faq-section {
  margin-top: 40px;
  padding-top: 28px;
  border-top: 1px solid var(--border-color);
}

.article-faq-title {
  font-size: 1.4rem;
  font-weight: 800;
  color: #ffffff;
  margin-bottom: 20px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.article-faq-title::before {
  content: "";
  display: inline-block;
  width: 4px;
  height: 20px;
  background: var(--accent-cyan);
  border-radius: 2px;
}

.article-faq-item {
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 18px 20px;
  margin-bottom: 14px;
  transition: var(--transition);
}

.article-faq-item:hover {
  border-color: var(--border-glow);
  background: rgba(163, 230, 53, 0.03);
}

.article-faq-q {
  font-size: 1.02rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 8px;
  display: flex;
  align-items: baseline;
  gap: 8px;
}

.article-faq-q span {
  color: var(--accent-cyan);
  font-family: var(--font-mono, monospace);
  font-weight: 900;
}

.article-faq-a {
  font-size: 0.92rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin: 0;
}

/* Related Articles Internal Link Matrix */
.related-posts-section {
  margin-top: 40px;
  padding: 24px;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
}

.related-posts-title {
  font-size: 1.1rem;
  font-weight: 800;
  color: #ffffff;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.related-posts-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 12px;
}

.related-post-link {
  display: flex;
  flex-direction: column;
  padding: 12px 14px;
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  transition: var(--transition);
}

.related-post-link:hover {
  border-color: var(--accent-cyan);
  background: rgba(163, 230, 53, 0.05);
  transform: translateY(-2px);
}

.related-post-name {
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.4;
  margin-bottom: 4px;
}

.related-post-tag {
  font-size: 0.75rem;
  color: var(--accent-cyan);
}


.back-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--accent-cyan);
  font-size: 0.95rem;
  font-weight: 600;
  margin-bottom: 24px;
}

.back-link:hover {
  text-decoration: underline;
}

/* ==========================================================================
   Responsive Adaptations (@media)
   Strict Mobile Single Column & Finger-friendly Touch Optimization
   ========================================================================== */
@media (max-width: 1024px) {
  .nav-links {
    gap: 16px;
  }
  .nav-link {
    font-size: 0.88rem;
  }
}

@media (max-width: 992px) {
  .features-grid,
  .pricing-grid,
  .testimonials-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .pricing-card.featured {
    transform: none;
  }
  .pricing-card.featured:hover {
    transform: translateY(-4px);
  }
  
  .support-wrapper {
    grid-template-columns: 1fr;
    padding: 36px 28px;
  }
}

@media (max-width: 768px) {
  .nav-links {
    display: none; /* Keep mobile header clean */
  }

  .nav {
    height: 64px;
  }

  .hero {
    padding: 50px 0 40px;
  }

  .hero-title {
    font-size: 2.2rem;
    letter-spacing: -0.5px;
  }

  .hero-subtitle {
    font-size: 1rem;
    margin-bottom: 28px;
  }

  .hero-actions {
    flex-direction: column;
    width: 100%;
    gap: 12px;
  }

  .hero-actions .btn {
    width: 100%;
  }

  .hero-highlights {
    gap: 14px;
    flex-direction: column;
    align-items: flex-start;
    padding: 16px 20px;
    background: rgba(255, 255, 255, 0.02);
    border-radius: var(--radius-md);
  }

  .section {
    padding: 60px 0;
  }

  .section-title {
    font-size: 1.8rem;
  }

  /* Strict single column layout */
  .features-grid,
  .pricing-grid,
  .testimonials-grid,
  .support-grid {
    grid-template-columns: 1fr;
    gap: 20px;
  }

  .pricing-card {
    padding: 32px 24px;
  }

  .cta-banner {
    padding: 40px 20px;
  }

  .cta-banner h2 {
    font-size: 1.7rem;
  }

  .cta-banner .btn {
    width: 100%;
  }

  .footer-nav {
    flex-direction: column;
    gap: 18px;
  }

  /* Finger-friendly touch button boost for mobile */
  .btn {
    min-height: 48px;
    font-size: 1rem;
    padding: 12px 24px;
  }
}

/* ==========================================================================
   Accessibility: Reduced Motion Preference
   ========================================================================== */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}