: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); }

.section-header {
      margin-bottom: var(--gap-lg);
    }

.section-header h2 {
      margin-bottom: var(--gap-sm);
    }

.section-header .lead {
      margin-bottom: 0;
    }

/* Scroll reveal */
    .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);
    }

h1, .h1 {
      font-family: var(--font-display);
      font-size: var(--fs-h1);
      font-weight: 700;
      line-height: 1.1;
      letter-spacing: -0.02em;
    }

h2, .h2 {
      font-family: var(--font-display);
      font-size: var(--fs-h2);
      font-weight: 700;
      line-height: 1.15;
      letter-spacing: -0.015em;
    }

h3, .h3 {
      font-family: var(--font-display);
      font-size: var(--fs-h3);
      font-weight: 600;
      line-height: 1.35;
      letter-spacing: -0.005em;
    }

.lead {
      font-size: var(--fs-lead);
      line-height: 1.65;
      color: var(--muted);
      max-width: 56ch;
    }

.eyebrow {
      font-family: var(--font-mono);
      font-size: 12px;
      font-weight: 500;
      letter-spacing: 0.1em;
      text-transform: uppercase;
      color: var(--accent);
      margin: 0 0 var(--gap-md);
    }

.meta {
      font-family: var(--font-mono);
      font-size: var(--fs-meta);
      color: var(--muted);
    }

/* ---- Topnav ---- */
    .topnav {
      position: fixed;
      top: 0;
      left: 0;
      right: 0;
      z-index: 100;
      height: 64px;
      background: transparent;
      border-bottom: 1px solid transparent;
      transition: background 0.4s cubic-bezier(0.16, 1, 0.3, 1), border-color 0.4s, backdrop-filter 0.4s;
    }

.topnav nav a {
      font-size: 16px;
      font-weight: 500;
      color: rgba(255,255,255,0.55);
      transition: color 0.25s;
      position: relative;
      letter-spacing: 0.01em;
    }

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

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

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

.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;
    }

/* ---- Page Hero ---- */
    .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 .container {
      position: relative;
      z-index: 1;
    }

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

.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);
    }

/* ---- Platform Grid / Cards ---- */
    .platform-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: var(--gap-md);
    }

.platform-card {
      background: var(--surface-elevated);
      border: 1px solid var(--border);
      border-radius: var(--radius-lg);
      padding: 28px;
      transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1), border-color 0.3s, box-shadow 0.3s;
      display: flex;
      flex-direction: column;
      box-shadow: 0 1px 3px rgba(0,0,0,0.04);
    }

.platform-card:hover {
      transform: translateY(-4px);
      border-color: rgba(0,0,0,0.15);
      box-shadow: 0 4px 12px rgba(0,0,0,0.06);
    }

.platform-icon {
      width: 48px;
      height: 48px;
      border-radius: var(--radius);
      background: var(--surface);
      border: 1px solid var(--border);
      display: flex;
      align-items: center;
      justify-content: center;
      margin-bottom: 20px;
      flex-shrink: 0;
    }

.platform-icon svg {
      width: 24px;
      height: 24px;
      stroke: var(--fg);
      fill: none;
      stroke-width: 1.6;
    }

.platform-card h3 {
      font-size: 17px;
      font-weight: 600;
      margin-bottom: 10px;
      line-height: 1.3;
    }

.platform-card p {
      font-size: 14px;
      color: var(--muted);
      line-height: 1.6;
      flex: 1;
    }

.platform-card .platform-tag {
      display: inline-block;
      font-family: var(--font-mono);
      font-size: 11px;
      color: var(--muted);
      letter-spacing: 0.06em;
      margin-top: 16px;
      padding-top: 16px;
      border-top: 1px solid var(--border);
    }

/* ---- Timeline ---- */
    .timeline {
      position: relative;
      padding-left: 48px;
    }

.timeline::before {
      content: '';
      position: absolute;
      left: 15px;
      top: 8px;
      bottom: 8px;
      width: 2px;
      background: var(--border);
    }

.timeline-step {
      position: relative;
      padding-bottom: 48px;
    }

.timeline-step:last-child {
      padding-bottom: 0;
    }

.timeline-dot {
      position: absolute;
      left: -48px;
      top: 2px;
      width: 32px;
      height: 32px;
      border-radius: 50%;
      background: var(--accent);
      display: flex;
      align-items: center;
      justify-content: center;
      color: #ffffff;
      font-family: var(--font-mono);
      font-size: 13px;
      font-weight: 600;
      z-index: 1;
    }

.timeline-step h3 {
      font-size: 20px;
      font-weight: 600;
      margin-bottom: 8px;
    }

.timeline-step p {
      font-size: 15px;
      color: var(--muted);
      line-height: 1.7;
      max-width: 560px;
    }

.timeline-tag {
      display: inline-block;
      font-family: var(--font-mono);
      font-size: 11px;
      letter-spacing: 0.06em;
      color: var(--accent);
      margin-bottom: 6px;
    }

/* ---- Stats ---- */
    .stats-row {
      display: flex;
      gap: var(--gap-xl);
      flex-wrap: wrap;
    }

.stat-item {
      flex: 1;
      min-width: 140px;
    }

.stat-number {
      font-family: var(--font-display);
      font-size: 48px;
      font-weight: 700;
      line-height: 1;
      margin-bottom: 8px;
      letter-spacing: -0.02em;
    }

.stat-label {
      font-size: 14px;
      color: var(--muted);
    }

/* ---- CTA Section ---- */
    .cta-section {
      text-align: center;
      padding-block: var(--gap-xl);
    }

.cta-section h2 {
      margin-bottom: var(--gap-sm);
    }

.cta-section .lead {
      margin: 0 auto var(--gap-lg);
    }

.btn {
      display: inline-flex;
      align-items: center;
      gap: 10px;
      padding: 14px 32px;
      border-radius: var(--radius);
      border: 1px solid transparent;
      font-size: 16px;
      font-weight: 600;
      letter-spacing: 0.02em;
      transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    }

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

.btn-primary {
      background: var(--fg);
      color: var(--bg);
      border-color: var(--fg);
    }

.btn-primary:hover {
      background: transparent;
      color: var(--fg);
      border-color: var(--fg);
    }

.btn-primary:active {
      background: rgba(0,0,0,0.85);
    }

.btn-secondary {
      background: transparent;
      color: var(--fg);
      border-color: rgba(0,0,0,0.15);
    }

.btn-secondary:hover {
      border-color: rgba(0,0,0,0.4);
      background: rgba(0,0,0,0.04);
    }

.btn-secondary:active {
      background: rgba(0,0,0,0.06);
      border-color: rgba(0,0,0,0.3);
    }

.cta-buttons {
      display: flex;
      gap: 16px;
      justify-content: center;
      flex-wrap: wrap;
    }

/* ---- Feature Image ---- */
    .feature-image {
      border-radius: var(--radius-lg);
      overflow: hidden;
      background: var(--surface);
      border: 1px solid var(--border);
    }

.feature-image img {
      width: 100%;
      display: block;
    }

/* ---- Footer ---- */
    .pagefoot {
      padding-block: var(--gap-xl);
      border-top: 1px solid var(--border);
      color: var(--muted);
      font-size: 14px;
      background: var(--surface);
    }

.footer-inner {
      display: grid;
      grid-template-columns: 1.5fr auto auto auto;
      gap: var(--gap-xl);
      align-items: start;
    }

.footer-brand {
      font-family: var(--font-display);
      font-size: 18px;
      font-weight: 700;
      color: var(--fg);
      margin-bottom: 10px;
    }

.footer-col h4 {
      font-size: 12px;
      font-weight: 600;
      letter-spacing: 0.08em;
      text-transform: uppercase;
      color: rgba(0,0,0,0.45);
      margin-bottom: 16px;
    }

.footer-bottom {
      margin-top: var(--gap-xl);
      padding-top: var(--gap-lg);
      border-top: 1px solid var(--border);
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-size: 13px;
      color: rgba(0,0,0,0.4);
    }

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

/* ---- Focus visible ---- */
    :focus { outline: none; }

:focus-visible {
      outline: 2px solid var(--accent);
      outline-offset: 3px;
      border-radius: 4px;
    }

.btn:focus-visible { outline-offset: 4px; }

.topnav nav a:focus-visible { outline-offset: 6px; }

/* ---- Nav dropdowns ---- */
    .nav-dropdown {
      position: relative;
    }

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

.nav-dropdown > a::before {
      content: '';
      display: none;
    }

.nav-dropdown .dropdown-arrow {
      width: 8px;
      height: 8px;
      border-right: 1.5px solid currentColor;
      border-bottom: 1.5px solid currentColor;
      transform: rotate(45deg) translateY(-2px);
      transition: transform 0.25s;
      flex-shrink: 0;
      opacity: 0.6;
    }

.dropdown-menu {
      position: absolute;
      top: 100%;
      left: 50%;
      transform: translateX(-50%) translateY(4px);
      min-width: 180px;
      background: rgba(10,10,10,0.95);
      backdrop-filter: blur(20px) saturate(180%);
      -webkit-backdrop-filter: blur(20px) saturate(180%);
      border: 1px solid rgba(255,255,255,0.1);
      border-radius: var(--radius);
      padding: 8px 0;
      opacity: 0;
      pointer-events: none;
      transition: opacity 0.2s, transform 0.2s, background 0.3s, border-color 0.3s;
      box-shadow: 0 8px 24px rgba(0,0,0,0.3);
      z-index: 120;
    }

.topnav.scrolled .dropdown-menu {
      background: rgba(255,255,255,0.98);
      border-color: var(--border);
      box-shadow: 0 8px 24px rgba(0,0,0,0.08);
    }

.nav-dropdown:hover .dropdown-menu,
    .nav-dropdown:focus-within .dropdown-menu {
      opacity: 1;
      pointer-events: auto;
      transform: translateX(-50%) translateY(0);
    }

.nav-dropdown:hover .dropdown-arrow {
      transform: rotate(-135deg) translateY(-2px);
    }

.dropdown-menu a {
      display: block;
      padding: 10px 20px;
      font-size: 14px;
      font-weight: 500;
      color: rgba(255,255,255,0.7);
      white-space: nowrap;
      transition: background 0.15s, color 0.15s;
    }

.dropdown-menu a:hover {
      background: rgba(255,255,255,0.08);
      color: #ffffff;
    }

.topnav.scrolled .dropdown-menu a:hover {
      background: var(--surface);
      color: var(--fg);
    }

.dropdown-menu a::after {
      display: none !important;
    }

/* ---- Mobile Nav ---- */
    .nav-toggle {
      display: none;
      flex-direction: column;
      justify-content: center;
      gap: 5px;
      width: 40px;
      height: 40px;
      padding: 8px;
      border-radius: var(--radius);
      cursor: pointer;
      z-index: 110;
    }

.nav-toggle span {
      display: block;
      width: 100%;
      height: 2px;
      background: #ffffff;
      border-radius: 1px;
      transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1), opacity 0.2s;
      transform-origin: center;
    }

.topnav.scrolled .nav-toggle span {
      background: var(--fg);
    }

.mobile-nav {
      display: none;
    }

/* ---- Responsive ---- */
    @media (max-width: 1024px) {
      :root { --gutter: 32px; }
    }

@media (max-width: 920px) {
      .nav-toggle { display: flex; }
      .topnav nav { display: none; }
      .topnav > .container > .nav-cta { display: none; }
      .nav-toggle.active span {
        background: #ffffff !important;
      }
      .mobile-nav {
        display: flex;
        flex-direction: column;
        position: absolute;
        top: 64px;
        left: 0;
        right: 0;
        background: rgba(255, 255, 255, 0.98);
        backdrop-filter: blur(20px) saturate(180%);
        -webkit-backdrop-filter: blur(20px) saturate(180%);
        border-bottom: 1px solid var(--border);
        padding: 16px var(--gutter) 24px;
        gap: 8px;
        opacity: 0;
        transform: translateY(-8px);
        pointer-events: none;
        transition: opacity 0.3s cubic-bezier(0.16, 1, 0.3, 1), transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
      }
      .mobile-nav.open {
        opacity: 1;
        transform: translateY(0);
        pointer-events: auto;
      }
      .mobile-nav nav {
        display: flex;
        flex-direction: column;
        gap: 0;
      }
      .mobile-nav nav a {
        font-size: 16px;
        font-weight: 500;
        color: rgba(0, 0, 0, 0.75);
        padding: 14px 0;
        border-bottom: 1px solid var(--border);
        transition: color 0.2s;
      }
      .mobile-nav nav a:last-child { border-bottom: none; }
      .mobile-nav nav a:hover { color: #1a1a1a; }
      .mobile-nav nav a.active { color: #1a1a1a; }
      .mobile-nav .nav-cta {
        margin-top: 12px;
        text-align: center;
        font-size: 15px;
        font-weight: 600;
        color: #1a1a1a;
        padding: 12px 28px;
        border: 1px solid rgba(0, 0, 0, 0.25);
        border-radius: var(--radius);
        transition: all 0.25s;
      }
      .mobile-nav .nav-cta:hover {
        background: #1a1a1a;
        color: #ffffff;
        border-color: #1a1a1a;
      }

      .platform-grid { grid-template-columns: repeat(2, 1fr); }
      .footer-inner { grid-template-columns: 1fr 1fr; gap: var(--gap-lg); }
      .footer-bottom { flex-direction: column; gap: var(--gap-sm); text-align: center; }
      :root { --gutter: 24px; }

      .dropdown-menu {
        position: static;
        transform: none;
        min-width: 0;
        background: transparent;
        backdrop-filter: none;
        -webkit-backdrop-filter: none;
        border: none;
        border-radius: 0;
        padding: 0 0 0 16px;
        box-shadow: none;
        max-height: 0;
        overflow: hidden;
        opacity: 1;
        pointer-events: auto;
        transition: max-height 0.3s cubic-bezier(0.16, 1, 0.3, 1);
      }
      .nav-dropdown.open .dropdown-menu,
        .nav-dropdown:hover .dropdown-menu,
        .nav-dropdown:focus-within .dropdown-menu {
        max-height: 600px;
        overflow-y: auto;
        transform: none;
      }
      .dropdown-menu a {
        padding: 10px 0;
        font-size: 14px;
        border-bottom: 1px solid var(--border);
      }
      .dropdown-menu a:last-child {
        border-bottom: none;
      }
    }

@media (max-width: 640px) {
      .platform-grid { grid-template-columns: 1fr; }
      .footer-inner { grid-template-columns: 1fr; }
      .page-hero { padding-top: 120px; padding-bottom: 56px; }
      .cta-buttons { flex-direction: column; align-items: center; }
      .cta-buttons .btn { width: 100%; max-width: 320px; justify-content: center; }
      .stats-row { gap: var(--gap-lg); }
      .stat-number { font-size: 36px; }
    }

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

/* ===================== 无人机定制页 cu- 组件（PPT 版式） ===================== */
.cu-shots { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--gap-md); }

.cu-shot { margin: 0; background: var(--surface-elevated); border: 1px solid var(--border); border-radius: var(--radius-lg); overflow: hidden; transition: transform 0.35s cubic-bezier(0.16, 1, 0.3, 1), box-shadow 0.35s, border-color 0.35s; }

.cu-shot:hover { transform: translateY(-4px); box-shadow: 0 12px 32px rgba(0, 0, 0, 0.08); border-color: var(--accent); }

.cu-shot-media { aspect-ratio: 16 / 10; background: #ffffff; display: flex; align-items: center; justify-content: center; padding: 18px; }

.cu-shot-media img { max-width: 100%; max-height: 100%; width: auto; height: auto; object-fit: contain; }

.cu-shot figcaption { padding: 14px 20px; border-top: 1px solid var(--border); background: #f7f9fc; font-size: 15px; font-weight: 600; color: var(--fg); letter-spacing: 0.06em; display: flex; align-items: center; gap: 10px; }

.cu-shot figcaption::before { content: ''; width: 8px; height: 8px; flex-shrink: 0; background: var(--accent); border-radius: 2px; }

.cu-adv-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: var(--gap-md); }

.cu-adv-card { background: var(--surface-elevated); border: 1px solid var(--border); border-radius: var(--radius-lg); padding: 28px 26px; transition: transform 0.35s cubic-bezier(0.16, 1, 0.3, 1), box-shadow 0.35s, border-color 0.35s; }

.cu-adv-card:hover { transform: translateY(-4px); box-shadow: 0 12px 32px rgba(0, 0, 0, 0.08); border-color: var(--accent); }

.cu-adv-num { font-family: var(--font-mono); font-size: 13px; font-weight: 600; color: var(--accent); letter-spacing: 0.08em; display: inline-block; margin-bottom: 12px; padding: 2px 10px; border: 1px solid color-mix(in oklch, var(--accent) 35%, transparent); border-radius: 999px; background: var(--accent-soft); }

.cu-adv-card h3 { margin: 0 0 10px; font-size: 18px; }

.cu-adv-card p { margin: 0; font-size: 14.5px; color: var(--muted); line-height: 1.75; }

@media (max-width: 1024px) {
      .cu-adv-grid { grid-template-columns: 1fr; }
    }

@media (max-width: 640px) {
      .cu-shots { grid-template-columns: 1fr; }
      .cu-adv-card { padding: 22px 20px; }
    }

/* ===== 机型名称条美化 v2（深蓝渐变横幅 + 悬停箭头） ===== */
.cu-shot { box-shadow: 0 2px 10px rgba(21, 42, 77, 0.05); }
.cu-shot-media img { transition: transform 0.5s cubic-bezier(0.16, 1, 0.3, 1); }
.cu-shot:hover .cu-shot-media img { transform: scale(1.04); }

.cu-shot figcaption {
      display: flex;
      align-items: center;
      gap: 12px;
      padding: 15px 20px;
      border-top: 0;
      background: linear-gradient(135deg, #16294a 0%, #1e3a6e 100%);
      color: #ffffff;
      font-size: 16px;
      font-weight: 700;
      letter-spacing: 0.08em;
    }

.cu-shot figcaption::before {
      width: 10px;
      height: 10px;
      border-radius: 3px;
      background: linear-gradient(135deg, #2196ff, #0d6fd9);
      box-shadow: 0 0 0 3px rgba(33, 150, 255, 0.16);
    }

.cu-shot figcaption::after {
      content: '';
      margin-left: auto;
      width: 9px;
      height: 9px;
      flex-shrink: 0;
      border-right: 2px solid rgba(255, 255, 255, 0.9);
      border-bottom: 2px solid rgba(255, 255, 255, 0.9);
      transform: rotate(-45deg);
      transition: transform 0.35s cubic-bezier(0.16, 1, 0.3, 1);
    }

.cu-shot:hover figcaption::after { transform: rotate(-45deg) translate(3px, -3px); }

/* 名称条响应式：平板收窄、移动端加大触控舒适度 */
@media (max-width: 1024px) {
      .cu-shot figcaption { padding: 13px 16px; font-size: 15px; }
      .cu-shot-media { padding: 14px; }
    }

@media (max-width: 640px) {
      .cu-shot figcaption { padding: 14px 16px; font-size: 15.5px; gap: 10px; }
      .cu-shot figcaption::before { width: 9px; height: 9px; box-shadow: 0 0 0 2.5px rgba(33, 150, 255, 0.16); }
      .cu-shot-media { padding: 16px; aspect-ratio: 16 / 11; }
    }

@media (prefers-reduced-motion: reduce) {
      .cu-shot, .cu-shot-media img, .cu-shot figcaption::after { transition: none; }
      .cu-shot:hover .cu-shot-media img { transform: none; }
    }