:root {
      --bg:      #ffffff;
      --surface: #f7f7f8;
      --fg:      #1a1a1a;
      --muted:   #6b6b6b;
      --border:  #e5e5e5;
      --accent:  #1890ff;

      --accent-soft: color-mix(in oklch, var(--accent) 10%, transparent);
      --fg-soft:     color-mix(in oklch, var(--fg) 4%, transparent);
      --surface-alt: #f0f0f2;
      --surface-elevated: #ffffff;

      --font-display: 'Open Sans', system-ui, -apple-system, 'Segoe UI', 'Helvetica Neue', Arial, sans-serif;
      --font-body:    'Open Sans', system-ui, -apple-system, 'Segoe UI', 'Helvetica Neue', Arial, sans-serif;
      --font-mono:    ui-monospace, 'JetBrains Mono', 'SF Mono', Menlo, monospace;

      --fs-h1: clamp(36px, 5vw, 56px);
      --fs-h2: clamp(28px, 3.5vw, 42px);
      --fs-h3: 20px;
      --fs-lead: 18px;
      --fs-body: 16px;
      --fs-meta: 13px;

      --gap-xs: 8px;
      --gap-sm: 12px;
      --gap-md: 24px;
      --gap-lg: 40px;
      --gap-xl: 72px;
      --gap-2xl: 128px;
      --container: 1280px;
      --gutter: 48px;

      --radius: 8px;
      --radius-lg: 16px;
      --radius-xl: 24px;
    }

body {
      margin: 0;
      background: var(--bg);
      color: var(--fg);
      font-family: var(--font-body);
      font-size: var(--fs-body);
      line-height: 1.6;
      text-rendering: optimizeLegibility;
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }

.section {
      padding-block: clamp(72px, 10vw, var(--gap-2xl));
    }

.section-alt {
      background: var(--surface-alt);
    }

.section + .section { border-top: 1px solid var(--border); }

.reveal {
      opacity: 0;
      transform: translateY(32px);
      transition: opacity 0.5s cubic-bezier(0.16, 1, 0.3, 1), transform 0.5s cubic-bezier(0.16, 1, 0.3, 1);
    }

.reveal-item {
      opacity: 0;
      transform: translateY(24px);
      transition: opacity 0.45s cubic-bezier(0.16, 1, 0.3, 1), transform 0.45s cubic-bezier(0.16, 1, 0.3, 1);
    }

.reveal-item.visible {
      opacity: 1;
      transform: translateY(0);
    }

.eyebrow {
      font-family: var(--font-mono);
      font-size: 12px;
      font-weight: 600;
      letter-spacing: 0.12em;
      text-transform: uppercase;
      color: var(--accent);
      margin-bottom: var(--gap-sm);
    }

.topnav {
      position: fixed;
      top: 0;
      left: 0;
      right: 0;
      z-index: 100;
      height: 64px;
      background: transparent;
      border-bottom: 1px solid transparent;
      transition: background 0.3s, border-color 0.3s;
    }

.topnav nav a {
      font-size: 16px;
      font-weight: 500;
      color: rgba(255,255,255,0.65);
      transition: color 0.25s;
      position: relative;
      letter-spacing: 0.01em;
    }

.topnav nav a.active {
      color: #ffffff;
    }

.topnav nav a.active::after {
      transform: scaleX(1);
    }

.topnav.scrolled nav a.active { color: #1a1a1a; }

.nav-dropdown { position: relative; }

.nav-dropdown > a { display: flex; align-items: center; gap: 4px; }

.dropdown-arrow {
      width: 0; height: 0;
      border-left: 4px solid transparent;
      border-right: 4px solid transparent;
      border-top: 4px solid currentColor;
      transition: transform 0.25s;
      margin-top: 2px;
    }

.nav-dropdown:hover .dropdown-arrow { transform: rotate(180deg); }

.dropdown-menu {
      position: absolute;
      top: 100%;
      left: 50%;
      transform: translateX(-50%);
      min-width: 180px;
      background: rgba(10,10,10,0.95);
      backdrop-filter: blur(12px);
      border: 1px solid rgba(255,255,255,0.08);
      border-radius: var(--radius);
      padding: 8px 0;
      opacity: 0;
      pointer-events: none;
      transition: opacity 0.25s, background 0.3s;
      z-index: 200;
    }

.dropdown-menu a {
      display: block;
      padding: 10px 20px;
      font-size: 14px;
      color: rgba(255,255,255,0.7);
      transition: color 0.2s, background 0.2s;
    }

.dropdown-menu a:hover {
      color: #ffffff;
      background: rgba(255,255,255,0.06);
    }

.nav-dropdown:hover .dropdown-menu {
      opacity: 1;
      pointer-events: auto;
    }

.topnav.scrolled .dropdown-menu {
      background: rgba(255,255,255,0.98);
      border-color: rgba(0,0,0,0.08);
    }

.topnav.scrolled .dropdown-menu a:hover {
      color: #1a1a1a;
      background: rgba(0,0,0,0.04);
    }

.topnav .nav-cta {
      font-size: 15px;
      font-weight: 600;
      color: #ffffff;
      padding: 10px 28px;
      border: 1px solid rgba(255,255,255,0.3);
      border-radius: var(--radius);
      transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
      letter-spacing: 0.02em;
    }

.topnav .nav-cta:active {
      transform: scale(0.96);
      transition-duration: 0.1s;
    }

.nav-toggle {
      display: none;
      flex-direction: column;
      gap: 5px;
      padding: 8px;
    }

.nav-toggle span {
      display: block;
      width: 22px;
      height: 2px;
      background: #ffffff;
      border-radius: 2px;
      transition: all 0.3s;
    }

.topnav.scrolled .nav-toggle span { background: #1a1a1a; }

.nav-toggle.active span { background: #fff; }

.mobile-nav {
      display: none;
      position: fixed;
      top: 64px;
      left: 0;
      right: 0;
      bottom: 0;
      background: rgba(255,255,255,0.98);
      backdrop-filter: blur(20px);
      padding: 32px var(--gutter);
      opacity: 0;
      pointer-events: none;
      transition: opacity 0.3s;
      z-index: 99;
      overflow-y: auto;
    }

.mobile-nav.open {
      opacity: 1;
      pointer-events: auto;
    }

.mobile-nav nav {
      display: flex;
      flex-direction: column;
      gap: 0;
    }

.mobile-nav nav a {
      display: block;
      padding: 16px 0;
      font-size: 18px;
      font-weight: 500;
      color: rgba(0,0,0,0.75);
      border-bottom: 1px solid var(--border);
    }

.mobile-nav .nav-cta {
      display: block;
      text-align: center;
      margin-top: 24px;
      padding: 14px;
      font-size: 16px;
      font-weight: 600;
      color: #1a1a1a;
      border: 1px solid rgba(0,0,0,0.3);
      border-radius: var(--radius);
    }

.mobile-nav .nav-dropdown .dropdown-menu {
      position: static;
      transform: none;
      background: transparent;
      border: none;
      padding: 0 0 0 16px;
      max-height: 0;
      overflow: hidden;
      opacity: 1;
      pointer-events: auto;
      transition: max-height 0.3s;
    }

.mobile-nav .nav-dropdown.open .dropdown-menu,
      .mobile-nav .nav-dropdown:hover .dropdown-menu,
      .mobile-nav .nav-dropdown:focus-within .dropdown-menu {
      max-height: 600px;
      overflow-y: auto;
      transform: none;
    }

.mobile-nav .nav-dropdown .dropdown-menu a {
      font-size: 15px;
      padding: 12px 0;
      color: rgba(0,0,0,0.55);
    }

@media (max-width: 920px) {
      .topnav nav, .topnav .nav-cta { display: none; }
      .nav-toggle { display: flex; }
      .mobile-nav { display: block; }
    }

.page-hero {
      position: relative;
      padding-top: 160px;
      padding-bottom: 80px;
      background: #000000;
      color: #ffffff;
      overflow: hidden;
    }

.page-hero::before {
      content: '';
      position: absolute;
      top: 0; left: 0; right: 0; bottom: 0;
      background: radial-gradient(ellipse 80% 60% at 50% 0%, rgba(24,144,255,0.06) 0%, transparent 70%);
      pointer-events: none;
    }

.page-hero h1 {
      font-size: var(--fs-h1);
      font-weight: 700;
      letter-spacing: -0.02em;
      line-height: 1.1;
      color: #ffffff;
    }

.page-hero .lead {
      font-size: var(--fs-lead);
      color: rgba(255,255,255,0.7);
      max-width: 640px;
      margin-top: var(--gap-md);
      line-height: 1.7;
    }

.page-hero .eyebrow { color: var(--accent); }

.breadcrumb {
      display: flex;
      align-items: center;
      gap: 8px;
      font-size: 13px;
      color: rgba(255,255,255,0.5);
      margin-bottom: var(--gap-md);
    }

.breadcrumb a { color: rgba(255,255,255,0.5); transition: color 0.2s; }

.breadcrumb a:hover { color: #ffffff; }

.breadcrumb .sep { color: rgba(255,255,255,0.3); }

.content-section {
      padding-block: var(--gap-2xl);
    }

.content-section + .content-section {
      border-top: 1px solid var(--border);
    }

.content-section h2 {
      font-size: var(--fs-h2);
      font-weight: 700;
      letter-spacing: -0.01em;
      margin-bottom: var(--gap-md);
      line-height: 1.2;
    }

.content-section .desc {
      font-size: var(--fs-body);
      color: var(--muted);
      line-height: 1.8;
      max-width: 720px;
    }

.content-section .desc strong {
      color: var(--fg);
      font-weight: 600;
    }

.tech-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: var(--gap-md);
      margin-top: var(--gap-lg);
    }

.tech-card {
      background: var(--surface-elevated);
      border: 1px solid var(--border);
      border-radius: var(--radius-lg);
      padding: var(--gap-lg);
      transition: border-color 0.3s, transform 0.3s;
    }

.tech-card:hover {
      border-color: #d0d0d0;
      transform: translateY(-2px);
    }

.tech-card .tech-icon {
      width: 48px;
      height: 48px;
      margin-bottom: var(--gap-md);
      color: var(--fg);
    }

.tech-card h3 {
      font-size: var(--fs-h3);
      font-weight: 600;
      margin-bottom: var(--gap-sm);
    }

.tech-card p {
      font-size: 14px;
      color: var(--muted);
      line-height: 1.7;
    }

.cta-section {
      background: var(--surface-alt);
      padding-block: var(--gap-2xl);
      text-align: center;
    }

.cta-section h2 {
      font-size: var(--fs-h2);
      font-weight: 700;
      margin-bottom: var(--gap-md);
    }

.cta-section .lead {
      font-size: var(--fs-lead);
      color: var(--muted);
      max-width: 560px;
      margin: 0 auto var(--gap-lg);
      line-height: 1.7;
    }

.cta-buttons {
      display: flex;
      gap: var(--gap-md);
      justify-content: center;
      flex-wrap: wrap;
    }

.btn {
      display: inline-flex;
      align-items: center;
      padding: 14px 32px;
      font-size: 15px;
      font-weight: 600;
      border-radius: var(--radius);
      transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
      letter-spacing: 0.02em;
    }

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

.btn-primary:hover {
      background: #0070d9;
      transform: translateY(-1px);
    }

.btn-primary:active { transform: scale(0.97); transition-duration: 0.1s; }

.btn-secondary {
      background: transparent;
      color: var(--fg);
      border: 1px solid rgba(0,0,0,0.2);
    }

.btn-secondary:hover {
      border-color: rgba(0,0,0,0.4);
      background: var(--surface-alt);
    }

.btn-secondary:active { transform: scale(0.97); transition-duration: 0.1s; }

.pagefoot {
      background: var(--surface);
      padding-block: var(--gap-xl);
      border-top: 1px solid var(--border);
    }

.footer-inner {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: var(--gap-xl);
    }

.footer-brand {
      font-size: 18px;
      font-weight: 700;
      margin-bottom: var(--gap-sm);
    }

.footer-desc {
      max-width: 32ch;
      font-size: 13px;
      color: var(--muted);
      line-height: 1.7;
    }

.footer-col h4 {
      font-size: 13px;
      font-weight: 600;
      color: rgba(0,0,0,0.5);
      text-transform: uppercase;
      letter-spacing: 0.08em;
      margin-bottom: var(--gap-md);
    }

.footer-bottom {
      display: flex;
      justify-content: space-between;
      margin-top: var(--gap-xl);
      padding-top: var(--gap-md);
      border-top: 1px solid var(--border);
      font-size: 13px;
      color: rgba(0,0,0,0.45);
    }

@media (max-width: 768px) {
      .tech-grid { grid-template-columns: repeat(2, 1fr); }
      .footer-inner { grid-template-columns: 1fr 1fr; gap: var(--gap-lg); }
    }

@media (max-width: 640px) {
      .tech-grid { grid-template-columns: 1fr; }
      .footer-inner { grid-template-columns: 1fr; }
      .footer-bottom { flex-direction: column; gap: 8px; }
    }

@media (prefers-reduced-motion: reduce) {
      .reveal, .reveal-item { opacity: 1; transform: none; transition: none; }
      .tech-card { transition: none; }
      .btn { transition: none; }
    }

/* ===== PPT 内容补充样式（八大技术 / 技术简介）===== */

.section-title {
      font-size: var(--fs-h2);
      font-weight: 700;
      letter-spacing: -0.01em;
      margin-bottom: var(--gap-md);
      line-height: 1.2;
    }

.section-desc {
      font-size: var(--fs-body);
      color: var(--muted);
      line-height: 1.8;
      max-width: 720px;
      margin: 0 0 var(--gap-md);
    }

.content-section .section-title + .section-desc { margin-top: calc(-1 * var(--gap-sm)); }

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

.tech-icon-img {
      width: 48px;
      height: 48px;
      object-fit: contain;
      margin-bottom: var(--gap-md);
      border-radius: 6px;
    }

.feature-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: var(--gap-md);
      margin-top: var(--gap-lg);
    }

.feature-item {
      background: var(--surface-elevated);
      border: 1px solid var(--border);
      border-radius: var(--radius-lg);
      padding: var(--gap-md) var(--gap-lg);
    }

.feature-item strong {
      display: block;
      font-size: var(--fs-h3);
      font-weight: 600;
      margin-bottom: 6px;
    }

.feature-item span {
      font-size: 14px;
      color: var(--muted);
      line-height: 1.7;
    }

.diagram-row {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: var(--gap-md);
      margin-top: var(--gap-lg);
    }

.diagram-figure {
      background: var(--surface-elevated);
      border: 1px solid var(--border);
      border-radius: var(--radius-lg);
      padding: var(--gap-md);
      text-align: center;
    }

.diagram-figure img {
      width: 100%;
      height: 280px;
      object-fit: contain;
      border-radius: 6px;
      display: block;
    }

.diagram-figure figcaption {
      margin-top: var(--gap-sm);
      font-size: 13px;
      color: var(--muted);
      line-height: 1.6;
    }

.spec-list {
      list-style: none;
      margin-top: var(--gap-md);
      display: grid;
      gap: var(--gap-sm);
    }

.spec-list li {
      background: var(--surface-elevated);
      border: 1px solid var(--border);
      border-radius: var(--radius-lg);
      padding: var(--gap-sm) var(--gap-md);
      font-size: 14px;
      color: var(--fg);
      line-height: 1.7;
    }

.spec-list li strong { color: var(--accent); font-weight: 600; }

.duo-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: var(--gap-lg);
      margin-top: var(--gap-lg);
      align-items: start;
    }

.img-strip {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: var(--gap-md);
      margin-top: var(--gap-md);
    }

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

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

.img-strip-one  { grid-template-columns: 1fr; }

.img-strip-one img { max-width: 460px; margin-inline: auto; }

.img-strip figure {
      background: var(--surface-elevated);
      border: 1px solid var(--border);
      border-radius: var(--radius-lg);
      padding: var(--gap-sm);
      text-align: center;
    }

.img-strip img {
      width: 100%;
      height: auto;
      border-radius: 6px;
      display: block;
    }

.img-strip figcaption {
      margin-top: 8px;
      font-size: 12px;
      color: var(--muted);
      line-height: 1.5;
    }

@media (max-width: 1024px) {
      .tech-grid-four { grid-template-columns: repeat(2, 1fr); }
    }

@media (max-width: 768px) {
      .feature-grid, .diagram-row, .duo-grid { grid-template-columns: 1fr; }
      .diagram-figure img { height: 320px; }
    }

@media (max-width: 640px) {
      .tech-grid-four { grid-template-columns: 1fr; }
      .img-strip, .img-strip-two, .img-strip-four { grid-template-columns: 1fr 1fr; }
      .tech-card .img-strip, .tech-card .img-strip-two, .tech-card .img-strip-four { grid-template-columns: 1fr; }
    }

/* ============================================================
   AI 板块图片卡统一（tech-ai）——三卡图片/文字等高
   ============================================================ */
[data-od-id="tech-ai"] .img-strip figure {
  display: flex;
  flex-direction: column;
}
[data-od-id="tech-ai"] .img-strip img {
  width: 100%;
  height: 180px;
  object-fit: cover;
}
[data-od-id="tech-ai"] .img-strip figcaption {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 40px;
  margin-top: 10px;
}