/* ==========================================================================
   0u0 网络加速器 - 极简瑞士风 Design System (Swiss Style CSS)
   ========================================================================== */

/* --- CSS Variables / Design Tokens --- */
:root {
  --font-primary: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-brand: "Arial Rounded MT Bold", "Rounded Mplus 1c", system-ui, -apple-system, sans-serif;
  
  --bg-main: #FAFAFA;
  --bg-card: #FFFFFF;
  --bg-dark: #0F172A;
  --bg-subtle: #F1F5F9;
  
  --text-main: #0F172A;
  --text-muted: #64748B;
  --text-light: #94A3B8;
  --text-white: #FFFFFF;
  
  --primary-color: #D90429;
  --primary-hover: #EF233C;
  --primary-light: #FFEBEE;
  
  --border-color: #E2E8F0;
  --border-dark: #334155;
  
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.05);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
  --shadow-lg: 0 12px 32px rgba(0,0,0,0.12);
  
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-full: 9999px;
  
  --transition-fast: 0.15s ease;
  --transition-normal: 0.25s ease;
  --max-width: 1200px;
}

/* --- Base Reset & Reset --- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-primary);
  background-color: var(--bg-main);
  color: var(--text-main);
  line-height: 1.6;
  overflow-x: hidden;
}

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

:focus-visible {
  outline: 3px solid var(--primary-color);
  outline-offset: 2px;
}

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 {
  color: var(--text-main);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.25;
}

h1 { font-size: clamp(2.2rem, 5vw, 3.8rem); }
h2 { font-size: clamp(1.8rem, 3.5vw, 2.5rem); }
h3 { font-size: clamp(1.25rem, 2vw, 1.5rem); }

p {
  color: var(--text-muted);
  margin-bottom: 1rem;
}

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

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

.brand-logo-text {
  font-family: var(--font-brand);
  font-weight: 900;
  letter-spacing: -0.05em;
  color: var(--text-main);
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
}

.brand-logo-text .accent {
  color: var(--primary-color);
}

/* --- Swiss Grid Container --- */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* --- Header / Navigation --- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  transition: background-color var(--transition-normal);
}

.nav-wrapper {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4.5rem;
}

.logo-link {
  font-size: 1.8rem;
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.logo-badge {
  background: var(--text-main);
  color: var(--text-white);
  font-size: 0.75rem;
  padding: 0.15rem 0.5rem;
  border-radius: var(--radius-sm);
  font-weight: 700;
  letter-spacing: 0.05em;
}

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

.nav-link {
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--text-main);
  padding: 0.5rem 0;
  position: relative;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0%;
  height: 2px;
  background-color: var(--primary-color);
  transition: width var(--transition-fast);
}

.nav-link:hover::after,
.nav-link.active::after {
  width: 100%;
}

.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text-main);
  padding: 0.5rem;
}

/* --- Buttons & CTAs --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.6rem;
  padding: 0.85rem 1.8rem;
  font-size: 1rem;
  font-weight: 700;
  border-radius: var(--radius-md);
  border: 2px solid transparent;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-align: center;
  min-height: 48px;
  white-space: nowrap;
}

.btn-primary {
  background-color: var(--primary-color);
  color: var(--text-white);
  box-shadow: 0 4px 14px rgba(217, 4, 41, 0.35);
}

.btn-primary:hover {
  background-color: var(--primary-hover);
  color: var(--text-white);
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(217, 4, 41, 0.45);
}

.btn-secondary {
  background-color: var(--bg-card);
  color: var(--text-main);
  border-color: var(--border-color);
}

.btn-secondary:hover {
  border-color: var(--text-main);
  background-color: var(--bg-subtle);
  transform: translateY(-2px);
}

.btn-block {
  width: 100%;
}

/* --- Main Sections Setup --- */
.section {
  padding: 5rem 0;
  position: relative;
}

.section-bg-alt {
  background-color: #F8FAFC;
  border-top: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
}

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

.section-tag {
  display: inline-block;
  font-size: 0.85rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--primary-color);
  background-color: var(--primary-light);
  padding: 0.35rem 0.85rem;
  border-radius: var(--radius-full);
  margin-bottom: 1rem;
}

.section-title {
  margin-bottom: 1rem;
}

.section-subtitle {
  font-size: 1.1rem;
  color: var(--text-muted);
}

/* --- Section 1: Hero --- */
.hero-section {
  padding: 6rem 0 5rem 0;
  overflow: hidden;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3.5rem;
  align-items: center;
}

.hero-content {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
}

.hero-badge-group {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.4rem 1rem;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-full);
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 1.5rem;
  box-shadow: var(--shadow-sm);
}

.hero-title {
  margin-bottom: 1.5rem;
  line-height: 1.15;
}

.hero-title span.highlight {
  color: var(--primary-color);
  position: relative;
  display: inline-block;
}

.hero-desc {
  font-size: 1.2rem;
  line-height: 1.6;
  margin-bottom: 2.5rem;
  color: var(--text-muted);
}

.hero-cta-group {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  width: 100%;
}

.hero-features-list {
  display: flex;
  gap: 1.5rem;
  margin-top: 2rem;
  font-size: 0.9rem;
  color: var(--text-muted);
  font-weight: 600;
}

.hero-features-list item {
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

/* Swiss Card Graphic */
.hero-visual {
  position: relative;
  width: 100%;
}

.swiss-card-hero {
  background: var(--bg-dark);
  color: var(--text-white);
  border-radius: var(--radius-lg);
  padding: 2.5rem;
  box-shadow: var(--shadow-lg);
  position: relative;
  border: 1px solid var(--border-dark);
}

.hero-graphic-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid rgba(255,255,255,0.1);
  padding-bottom: 1.25rem;
  margin-bottom: 1.5rem;
}

.graphic-dots {
  display: flex;
  gap: 0.4rem;
}

.graphic-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: rgba(255,255,255,0.2);
}

.graphic-dot.red { background: #EF4444; }
.graphic-dot.yellow { background: #F59E0B; }
.graphic-dot.green { background: #10B981; }

.status-indicator {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.85rem;
  color: #10B981;
  font-weight: 700;
}

.status-dot {
  width: 8px;
  height: 8px;
  background: #10B981;
  border-radius: 50%;
  box-shadow: 0 0 10px #10B981;
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.5; transform: scale(1.2); }
  100% { opacity: 1; transform: scale(1); }
}

.speed-meter-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.meter-box {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.1);
  padding: 1.25rem;
  border-radius: var(--radius-md);
}

.meter-box .label {
  font-size: 0.8rem;
  color: var(--text-light);
  margin-bottom: 0.25rem;
}

.meter-box .val {
  font-size: 1.8rem;
  font-weight: 900;
  font-family: monospace;
  color: #FFFFFF;
}

.node-list-preview {
  background: rgba(0,0,0,0.3);
  border-radius: var(--radius-md);
  padding: 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.node-item-mini {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
}

.node-flag-name {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.ping-tag {
  font-family: monospace;
  font-size: 0.75rem;
  color: #10B981;
  background: rgba(16, 185, 129, 0.15);
  padding: 0.15rem 0.4rem;
  border-radius: 4px;
}

/* --- Section 2: Core Advantages --- */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
}

.feature-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 2.25rem;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast), border-color var(--transition-fast);
  display: flex;
  flex-direction: column;
}

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

.feature-icon-wrapper {
  width: 3.5rem;
  height: 3.5rem;
  background-color: var(--primary-light);
  color: var(--primary-color);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  margin-bottom: 1.5rem;
}

.feature-title {
  margin-bottom: 0.75rem;
  font-size: 1.3rem;
}

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

/* --- Section 3: Streaming & AI Support --- */
.services-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.5rem;
}

.service-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  text-align: center;
  transition: all var(--transition-fast);
}

.service-card:hover {
  border-color: var(--text-main);
  box-shadow: var(--shadow-sm);
}

.service-icon {
  font-size: 2.5rem;
  margin-bottom: 0.75rem;
  display: block;
}

.service-name {
  font-weight: 700;
  font-size: 1.1rem;
  margin-bottom: 0.25rem;
}

.service-tag {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* --- Section 4: Pricing --- */
.pricing-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
  align-items: stretch;
}

.pricing-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2.5rem 2rem;
  display: flex;
  flex-direction: column;
  position: relative;
  transition: all var(--transition-fast);
}

.pricing-card.popular {
  border: 2px solid var(--primary-color);
  box-shadow: var(--shadow-lg);
  transform: scale(1.02);
}

.popular-badge {
  position: absolute;
  top: -14px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--primary-color);
  color: var(--text-white);
  font-size: 0.8rem;
  font-weight: 800;
  padding: 0.25rem 1rem;
  border-radius: var(--radius-full);
  letter-spacing: 0.05em;
}

.pricing-header {
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 1.5rem;
  margin-bottom: 1.5rem;
}

.pricing-plan-name {
  font-size: 1.4rem;
  margin-bottom: 0.5rem;
}

.pricing-price-wrap {
  display: flex;
  align-items: baseline;
  gap: 0.25rem;
}

.currency {
  font-size: 1.25rem;
  font-weight: 700;
}

.price {
  font-size: 2.8rem;
  font-weight: 900;
  color: var(--text-main);
  line-height: 1;
}

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

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

.pricing-features li {
  padding: 0.6rem 0;
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-size: 0.95rem;
  color: var(--text-muted);
}

.pricing-features li strong {
  color: var(--text-main);
}

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

/* --- Section 5: FAQ --- */
.faq-list {
  max-width: 800px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

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

.faq-question {
  width: 100%;
  padding: 1.25rem 1.5rem;
  background: none;
  border: none;
  text-align: left;
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-main);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.faq-icon {
  font-size: 1.2rem;
  transition: transform var(--transition-fast);
}

.faq-answer {
  padding: 0 1.5rem 1.25rem 1.5rem;
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.6;
  display: none;
}

.faq-item.active .faq-answer {
  display: block;
}

.faq-item.active .faq-icon {
  transform: rotate(45deg);
}

/* --- Section Floating Navigation (Arrow Navigation Widget) --- */
.section-nav-arrows {
  position: fixed;
  right: 1.5rem;
  bottom: 50%;
  transform: translateY(50%);
  z-index: 990;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(8px);
  padding: 0.5rem;
  border-radius: var(--radius-full);
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-md);
}

.nav-arrow-btn {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-main);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  font-size: 1.1rem;
  transition: all var(--transition-fast);
}

.nav-arrow-btn:hover:not(:disabled) {
  background: var(--text-main);
  color: var(--text-white);
  border-color: var(--text-main);
}

.nav-arrow-btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

/* --- Footer --- */
.site-footer {
  background-color: var(--bg-dark);
  color: var(--text-white);
  padding: 4rem 0 2rem 0;
  border-top: 1px solid var(--border-dark);
}

.footer-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  padding-bottom: 2.5rem;
  margin-bottom: 2rem;
  flex-wrap: wrap;
  gap: 1.5rem;
}

.footer-brand {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.footer-brand .brand-logo-text {
  color: var(--text-white);
  font-size: 1.8rem;
}

.footer-brand p {
  color: var(--text-light);
  margin-bottom: 0;
  font-size: 0.9rem;
}

.footer-nav {
  display: flex;
  gap: 2rem;
  list-style: none;
}

.footer-nav a {
  color: var(--text-light);
  font-weight: 600;
  font-size: 0.95rem;
  transition: color var(--transition-fast);
}

.footer-nav a:hover {
  color: var(--text-white);
}

.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
  color: var(--text-light);
  flex-wrap: wrap;
  gap: 1rem;
}

/* --- Articles / Blog Styling --- */
.article-header {
  padding: 4rem 0 2rem 0;
  background: var(--bg-subtle);
  border-bottom: 1px solid var(--border-color);
  margin-bottom: 3rem;
}

.article-meta {
  display: flex;
  gap: 1.5rem;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-top: 1rem;
}

.article-content {
  max-width: 800px;
  margin: 0 auto;
  font-size: 1.05rem;
  line-height: 1.8;
  color: #334155;
}

.article-content h2 {
  margin: 2.5rem 0 1rem 0;
  font-size: 1.75rem;
}

.article-content h3 {
  margin: 2rem 0 0.85rem 0;
  font-size: 1.35rem;
}

.article-content p {
  margin-bottom: 1.5rem;
  color: #334155;
}

.article-content ul, .article-content ol {
  margin-bottom: 1.5rem;
  padding-left: 1.5rem;
}

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

.article-box-callout {
  background: var(--primary-light);
  border-left: 4px solid var(--primary-color);
  padding: 1.5rem;
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  margin: 2rem 0;
}

.article-box-callout h4 {
  color: var(--primary-color);
  margin-bottom: 0.5rem;
}

.article-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
}

.article-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  transition: all var(--transition-fast);
}

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

.article-card-date {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

.article-card-title {
  font-size: 1.2rem;
  margin-bottom: 0.75rem;
  line-height: 1.4;
}

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

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

.article-card-excerpt {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-bottom: 1.5rem;
  flex-grow: 1;
}

/* --- Responsive Media Queries --- */
@media (max-width: 992px) {
  .hero-grid {
    grid-template-columns: 1fr;
    gap: 2.5rem;
  }

  .features-grid,
  .pricing-grid,
  .article-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .services-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .pricing-card.popular {
    transform: none;
  }
}

@media (max-width: 768px) {
  .nav-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    background: var(--bg-card);
    flex-direction: column;
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
    box-shadow: var(--shadow-lg);
  }

  .nav-menu.active {
    display: flex;
  }

  .mobile-menu-btn {
    display: block;
  }

  .features-grid,
  .pricing-grid,
  .services-grid,
  .article-grid {
    grid-template-columns: 1fr;
  }

  .section-nav-arrows {
    right: 0.5rem;
    padding: 0.35rem;
  }

  .nav-arrow-btn {
    width: 36px;
    height: 36px;
    font-size: 0.9rem;
  }

  .footer-top {
    flex-direction: column;
    align-items: flex-start;
  }

  .footer-nav {
    flex-direction: column;
    gap: 0.75rem;
  }
}