/* ===== ChuranAI Unified Brand Website - Design System ===== */
/* Design direction: Business, international, trustworthy */
/* Colors: White/light gray background, deep blue brand color */

:root {
  --color-primary: #1a365d;
  --color-primary-light: #2b6cb0;
  --color-primary-dark: #0f2540;
  --color-accent: #c05621;
  --color-accent-light: #dd6b20;
  --color-bg: #ffffff;
  --color-bg-alt: #f7f8fa;
  --color-bg-card: #ffffff;
  --color-text: #1a202c;
  --color-text-secondary: #4a5568;
  --color-text-muted: #718096;
  --color-border: #e2e8f0;
  --color-border-light: #edf2f7;
  --color-success: #2f855a;
  --color-warning: #b7791f;
  --color-status-poc: #c05621;
  --color-status-internal: #718096;
  --color-status-pilot: #2b6cb0;
  --color-status-live: #2f855a;

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  --font-mono: "SF Mono", "Fira Code", "Consolas", monospace;

  --max-width: 1200px;
  --max-width-narrow: 800px;
  --max-width-wide: 1400px;

  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;

  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
  --shadow-lg: 0 10px 30px rgba(0,0,0,0.10);
  --shadow-xl: 0 20px 50px rgba(0,0,0,0.12);

  --transition: 0.2s ease;
}

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

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

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

img {
  max-width: 100%;
  height: auto;
  display: block;
}

ul, ol {
  list-style: none;
}

/* ===== Layout ===== */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

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

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

.section {
  padding: 80px 0;
}

.section-sm {
  padding: 48px 0;
}

.section-lg {
  padding: 120px 0;
}

.bg-alt {
  background: var(--color-bg-alt);
}

.bg-primary {
  background: var(--color-primary);
  color: #fff;
}

.bg-primary-dark {
  background: var(--color-primary-dark);
  color: #fff;
}

/* ===== Typography ===== */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.3;
  color: var(--color-text);
}

.bg-primary h1, .bg-primary h2, .bg-primary h3,
.bg-primary-dark h1, .bg-primary-dark h2, .bg-primary-dark h3 {
  color: #fff;
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }
h5 { font-size: 1.1rem; }

.text-center { text-align: center; }
.text-muted { color: var(--color-text-muted); }
.text-secondary { color: var(--color-text-secondary); }

.eyebrow {
  font-size: 0.85rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-primary-light);
  margin-bottom: 12px;
}

.lead {
  font-size: 1.2rem;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

/* ===== Header & Navigation ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255,255,255,0.98);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--color-border);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-primary);
  text-decoration: none;
  white-space: nowrap;
}

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

/* Existing brand logo (unchanged from current site) */
.nav-brand .brand-logo {
  flex-shrink: 0;
  display: block;
}

.nav-brand .brand-name {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--color-primary);
  line-height: 1.2;
}

/* ===== Bilingual language toggle (About / Contact / Privacy) ===== */
.lang-tabs {
  display: inline-flex;
  align-items: center;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  background: #fff;
}

.lang-tab {
  padding: 8px 18px;
  font-size: 0.9rem;
  font-weight: 600;
  font-family: inherit;
  background: #fff;
  color: var(--color-text-secondary);
  border: none;
  cursor: pointer;
  transition: all var(--transition);
}

.lang-tab + .lang-tab {
  border-left: 1px solid var(--color-border);
}

.lang-tab:hover {
  color: var(--color-primary);
  background: var(--color-bg-alt);
}

.lang-tab.active {
  background: var(--color-primary);
  color: #fff;
}

.lang-panel[hidden] {
  display: none;
}

.lang-switch-bar {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 32px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--color-border);
}

.lang-switch-bar .lang-switch-label {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  font-weight: 500;
}

@media (max-width: 768px) {
  .lang-tab {
    padding: 7px 14px;
    font-size: 0.85rem;
  }
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 4px;
}

.nav-link {
  display: inline-block;
  padding: 8px 16px;
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  text-decoration: none;
  border-radius: var(--radius-sm);
  transition: all var(--transition);
}

.nav-link:hover {
  color: var(--color-primary);
  background: var(--color-border-light);
}

.nav-link.active {
  color: var(--color-primary);
  font-weight: 600;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

.lang-switch {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 6px 12px;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  text-decoration: none;
  transition: all var(--transition);
}

.lang-switch:hover {
  border-color: var(--color-primary-light);
  color: var(--color-primary);
}

/* Mobile nav toggle */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  width: 40px;
  height: 40px;
  background: none;
  border: none;
  cursor: pointer;
  gap: 5px;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: all var(--transition);
}

.nav-toggle.open span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.nav-toggle.open span:nth-child(2) {
  opacity: 0;
}
.nav-toggle.open span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 28px;
  font-size: 0.95rem;
  font-weight: 600;
  border-radius: var(--radius-md);
  border: 2px solid transparent;
  cursor: pointer;
  transition: all var(--transition);
  text-decoration: none;
  white-space: nowrap;
}

.btn-primary {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
}

.btn-primary:hover {
  background: var(--color-primary-dark);
  border-color: var(--color-primary-dark);
  color: #fff;
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-secondary {
  background: #fff;
  color: var(--color-primary);
  border-color: var(--color-border);
}

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

.btn-accent {
  background: var(--color-accent);
  color: #fff;
  border-color: var(--color-accent);
}

.btn-accent:hover {
  background: var(--color-accent-light);
  border-color: var(--color-accent-light);
  color: #fff;
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-ghost {
  background: transparent;
  color: var(--color-primary);
  border-color: transparent;
  padding: 8px 16px;
}

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

.btn-lg {
  padding: 16px 36px;
  font-size: 1.05rem;
}

.btn-sm {
  padding: 8px 20px;
  font-size: 0.875rem;
}

.btn-block {
  width: 100%;
}

/* ===== Cards ===== */
.card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 32px;
  transition: all var(--transition);
}

.card:hover {
  border-color: var(--color-primary-light);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.card-flat {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 32px;
}

/* Business line card */
.biz-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 0;
  overflow: hidden;
  transition: all var(--transition);
  display: flex;
  flex-direction: column;
}

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

.biz-card-header {
  padding: 28px 32px 0;
}

.biz-card-tag {
  display: inline-block;
  padding: 4px 12px;
  font-size: 0.75rem;
  font-weight: 600;
  border-radius: 20px;
  margin-bottom: 16px;
}

.tag-cn { background: #ebf4ff; color: #2b6cb0; }
.tag-en { background: #fef5e7; color: #c05621; }
.tag-product { background: #f0fff4; color: #2f855a; }

.biz-card-body {
  padding: 0 32px 32px;
  flex: 1;
  display: flex;
  flex-direction: column;
}

.biz-card-body h3 {
  margin-bottom: 12px;
}

.biz-card-body p {
  color: var(--color-text-secondary);
  margin-bottom: 20px;
  flex: 1;
}

.biz-card-footer {
  padding-top: 16px;
}

/* Product card */
.product-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: all var(--transition);
}

.product-card:hover {
  border-color: var(--color-primary-light);
  box-shadow: var(--shadow-md);
}

.product-card-header {
  padding: 24px 28px 0;
}

.product-card-body {
  padding: 0 28px 24px;
}

.product-card-body h4 {
  margin-bottom: 8px;
}

.product-card-body p {
  color: var(--color-text-secondary);
  font-size: 0.95rem;
  margin-bottom: 16px;
}

/* Status badge */
.status-badge {
  display: inline-block;
  padding: 3px 10px;
  font-size: 0.75rem;
  font-weight: 600;
  border-radius: 4px;
  margin-bottom: 12px;
}

.status-live { background: #f0fff4; color: var(--color-status-live); }
.status-pilot { background: #ebf4ff; color: var(--color-status-pilot); }
.status-poc { background: #fef5e7; color: var(--color-status-poc); }
.status-internal { background: #edf2f7; color: var(--color-status-internal); }

/* ===== Grid System ===== */
.grid {
  display: grid;
  gap: 24px;
}

.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

/* ===== Hero Section ===== */
.hero {
  padding: 80px 0 64px;
  background: linear-gradient(180deg, var(--color-bg-alt) 0%, #fff 100%);
}

.hero h1 {
  font-size: 3rem;
  line-height: 1.25;
  margin-bottom: 24px;
  color: var(--color-primary);
}

.hero .lead {
  font-size: 1.3rem;
  max-width: 680px;
  margin-bottom: 40px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  align-items: center;
}

/* ===== Page Header ===== */
.page-header {
  padding: 64px 0 48px;
  background: var(--color-bg-alt);
  border-bottom: 1px solid var(--color-border);
}

.page-header h1 {
  color: var(--color-primary);
  margin-bottom: 16px;
}

.page-header .lead {
  max-width: 680px;
}

/* ===== Process Steps ===== */
.steps {
  display: grid;
  gap: 24px;
  counter-reset: step;
}

.step {
  display: flex;
  gap: 24px;
  align-items: flex-start;
}

.step-number {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  background: var(--color-primary);
  color: #fff;
  border-radius: 50%;
  font-size: 1.25rem;
  font-weight: 700;
}

.step-content h4 {
  margin-bottom: 8px;
}

.step-content p {
  color: var(--color-text-secondary);
}

/* ===== Feature List ===== */
.feature-list {
  display: grid;
  gap: 16px;
}

.feature-item {
  display: flex;
  gap: 16px;
  align-items: flex-start;
}

.feature-icon {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  background: #ebf4ff;
  border-radius: var(--radius-md);
  color: var(--color-primary-light);
  font-size: 1.25rem;
}

.feature-content h5 {
  margin-bottom: 4px;
}

.feature-content p {
  color: var(--color-text-secondary);
  font-size: 0.95rem;
}

/* ===== Info Table ===== */
.info-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.95rem;
}

.info-table th,
.info-table td {
  padding: 12px 16px;
  text-align: left;
  border-bottom: 1px solid var(--color-border);
}

.info-table th {
  font-weight: 600;
  color: var(--color-text);
  background: var(--color-bg-alt);
}

.info-table td {
  color: var(--color-text-secondary);
}

/* ===== CTA Section ===== */
.cta-section {
  padding: 64px 0;
  background: var(--color-primary);
  color: #fff;
}

.cta-section h2 {
  color: #fff;
  margin-bottom: 16px;
}

.cta-section p {
  color: rgba(255,255,255,0.85);
  font-size: 1.1rem;
  margin-bottom: 32px;
}

/* ===== Footer ===== */
.site-footer {
  background: var(--color-primary-dark);
  color: rgba(255,255,255,0.7);
  padding: 64px 0 0;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 48px;
  margin-bottom: 48px;
}

.footer-brand h4 {
  color: #fff;
  margin-bottom: 12px;
}

.footer-brand p {
  font-size: 0.9rem;
  line-height: 1.7;
  margin-bottom: 16px;
}

.footer-col h5 {
  color: #fff;
  font-size: 0.9rem;
  font-weight: 600;
  margin-bottom: 16px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.footer-col ul li {
  margin-bottom: 10px;
}

.footer-col ul li a {
  color: rgba(255,255,255,0.65);
  font-size: 0.9rem;
  text-decoration: none;
  transition: color var(--transition);
}

.footer-col ul li a:hover {
  color: #fff;
}

.footer-col .info-item {
  font-size: 0.9rem;
  color: rgba(255,255,255,0.65);
  margin-bottom: 8px;
  line-height: 1.6;
}

.footer-col .info-item strong {
  color: rgba(255,255,255,0.85);
}

.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.1);
  padding: 24px 0;
  font-size: 0.85rem;
}

.footer-bottom .filing-info {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  align-items: center;
  color: rgba(255,255,255,0.5);
}

.footer-bottom .filing-info a {
  color: rgba(255,255,255,0.5);
  text-decoration: none;
}

.footer-bottom .filing-info a:hover {
  color: rgba(255,255,255,0.8);
}

/* 公安网安备案：图标 + 文字（保持与备案机构链接一致，图标不可变更） */
.footer-bottom .filing-info a.gongan {
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

.footer-bottom .filing-info a.gongan img {
  width: 14px;
  height: 14px;
  display: inline-block;
  vertical-align: middle;
}

.footer-bottom .static-notice {
  width: 100%;
  margin-top: 8px;
  color: rgba(255,255,255,0.4);
  font-size: 0.8rem;
}

/* ===== Contact Info Block ===== */
.contact-block {
  background: var(--color-bg-alt);
  border-radius: var(--radius-lg);
  padding: 32px;
  border: 1px solid var(--color-border);
}

.contact-item {
  display: flex;
  gap: 16px;
  margin-bottom: 24px;
  align-items: flex-start;
}

.contact-item:last-child {
  margin-bottom: 0;
}

.contact-icon {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  background: var(--color-primary);
  color: #fff;
  border-radius: var(--radius-md);
  font-size: 1.2rem;
}

.contact-detail h5 {
  margin-bottom: 4px;
}

.contact-detail p,
.contact-detail a {
  color: var(--color-text-secondary);
  font-size: 0.95rem;
}

/* ===== Divider ===== */
.divider {
  height: 1px;
  background: var(--color-border);
  margin: 48px 0;
}

/* ===== Badge Row ===== */
.badge-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 16px;
}

.badge {
  display: inline-block;
  padding: 4px 12px;
  font-size: 0.8rem;
  font-weight: 500;
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: 20px;
  color: var(--color-text-secondary);
}

/* ===== Alert / Notice ===== */
.notice {
  display: flex;
  gap: 12px;
  padding: 16px 20px;
  background: #fffaf0;
  border: 1px solid #fbd38d;
  border-radius: var(--radius-md);
  margin-bottom: 24px;
}

.notice-icon {
  flex-shrink: 0;
  color: var(--color-warning);
}

.notice p {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
}

/* ===== Responsive ===== */
@media (max-width: 1024px) {
  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 768px) {
  .nav-menu {
    display: none;
    position: fixed;
    top: 64px;
    left: 0;
    right: 0;
    background: #fff;
    border-bottom: 1px solid var(--color-border);
    flex-direction: column;
    padding: 16px;
    gap: 0;
    box-shadow: var(--shadow-lg);
  }

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

  .nav-menu .nav-link {
    display: block;
    padding: 14px 16px;
    border-radius: 0;
    border-bottom: 1px solid var(--color-border-light);
  }

  .nav-toggle {
    display: flex;
  }

  .nav-actions {
    gap: 8px;
  }

  .lang-switch {
    padding: 6px 8px;
    font-size: 0.8rem;
  }

  .hero {
    padding: 48px 0 32px;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .hero .lead {
    font-size: 1.1rem;
  }

  .hero-actions {
    flex-direction: column;
    align-items: stretch;
  }

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

  .section {
    padding: 48px 0;
  }

  .section-lg {
    padding: 64px 0;
  }

  h1 { font-size: 1.875rem; }
  h2 { font-size: 1.5rem; }
  h3 { font-size: 1.25rem; }

  .grid-2,
  .grid-3,
  .grid-4 {
    grid-template-columns: 1fr;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .container,
  .container-narrow,
  .container-wide {
    padding: 0 16px;
  }

  .card,
  .card-flat,
  .biz-card-header,
  .biz-card-body,
  .product-card-header,
  .product-card-body {
    padding-left: 20px;
    padding-right: 20px;
  }

  .step {
    flex-direction: column;
    gap: 12px;
  }
}

@media (max-width: 480px) {
  .hero h1 {
    font-size: 1.6rem;
  }

  .btn {
    padding: 10px 24px;
    font-size: 0.9rem;
  }
}