/* ============================================================
   帧流算力 · Seedance 2.5 算力 H5 —— 高端克制风
   设计语言：深色科技质感 · 减法与精细化
   - 底色 Zinc-950 系（杜绝纯黑）
   - 单一强调色 Sky-400（降饱和，无 AI 紫蓝）
   - Display 用 Sora，正文系统无衬线（禁用 Inter）
   - 质感靠排版 / 层次 / 细边框，禁用外发光
   ============================================================ */

:root {
  /* 底色与面板 */
  --bg: #09090b;
  --bg-soft: #0e0e11;
  --panel: #111114;
  --panel-2: #15151a;
  --panel-3: #1a1a20;

  /* 边框 */
  --line: rgba(255, 255, 255, 0.07);
  --line-strong: rgba(255, 255, 255, 0.13);
  --line-accent: rgba(45, 212, 191, 0.38);

  /* 文字层次 */
  --text-hi: #f4f4f5;
  --text: #e4e4e7;
  --text-2: #a1a1aa;
  --text-3: #71717a;

  /* 强调色（Teal-400，青绿蓝绿，降饱和） */
  --accent: #2dd4bf;
  --accent-soft: rgba(45, 212, 191, 0.1);
  --accent-mid: rgba(45, 212, 191, 0.55);
  --on-accent: #042a25;

  /* 字体 */
  --font-display: "Sora", ui-sans-serif, system-ui, -apple-system, "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-body: ui-sans-serif, system-ui, -apple-system, "PingFang SC", "Microsoft YaHei", sans-serif;

  /* 圆角（克制收敛） */
  --radius-sm: 10px;
  --radius: 14px;
  --radius-lg: 18px;

  /* 过渡 */
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  /* 极淡网格纹理，营造精密感 */
  background-image: radial-gradient(circle at 1px 1px, rgba(255, 255, 255, 0.028) 1px, transparent 0);
  background-size: 34px 34px;
  color: var(--text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a {
  color: inherit;
  text-decoration: none;
}

button,
textarea,
select {
  font: inherit;
}

::selection {
  background: rgba(45, 212, 191, 0.25);
  color: var(--text-hi);
}

/* ---------- Header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 16px clamp(18px, 4vw, 60px);
  background: rgba(9, 9, 11, 0.78);
  -webkit-backdrop-filter: blur(18px) saturate(1.2);
  backdrop-filter: blur(18px) saturate(1.2);
  border-bottom: 1px solid var(--line);
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 15px;
  letter-spacing: 0.01em;
  color: var(--text-hi);
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 32px;
  height: 32px;
  border: 1px solid var(--line-accent);
  border-radius: 9px;
  background: linear-gradient(135deg, var(--accent-soft), rgba(9, 9, 11, 0.4));
}

.brand-mark svg {
  width: 18px;
  height: 18px;
  fill: var(--accent);
}

.nav {
  display: flex;
  align-items: center;
  gap: 26px;
  color: var(--text-2);
  font-size: 14px;
}

.nav a {
  position: relative;
  transition: color 0.18s ease;
}

.nav a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -4px;
  width: 0;
  height: 1px;
  background: var(--accent-mid);
  transition: width 0.22s var(--ease);
}

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

.nav a:hover::after {
  width: 100%;
}

.header-cta {
  padding: 9px 18px;
  border: 1px solid var(--line-accent);
  border-radius: 999px;
  color: var(--accent);
  font-size: 14px;
  font-weight: 600;
  background: transparent;
  transition: background 0.2s ease, color 0.2s ease;
}

.header-cta:hover {
  background: var(--accent-soft);
  color: var(--accent);
}

.menu-toggle {
  display: none;
  background: transparent;
  border: 0;
  gap: 4px;
  flex-direction: column;
  cursor: pointer;
}

.menu-toggle span {
  width: 22px;
  height: 2px;
  background: var(--text);
  border-radius: 999px;
}

/* ---------- 通用区块 ---------- */
.section-shell {
  width: min(1120px, calc(100% - 40px));
  margin: 0 auto;
  padding: 96px 0;
}

.eyebrow {
  margin: 0 0 16px;
  color: var(--accent);
  font-family: var(--font-display);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
}

.hero h1,
.section-shell h2 {
  margin: 0;
  color: var(--text-hi);
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.08;
  letter-spacing: -0.03em;
}

.hero h1 {
  font-size: clamp(40px, 6.5vw, 76px);
  font-weight: 700;
}

.section-shell h2 {
  font-size: clamp(28px, 3.6vw, 48px);
}

.hero-lead,
.section-lead {
  max-width: 640px;
  color: var(--text-2);
  font-size: 17px;
  line-height: 1.75;
}

/* ---------- Hero ---------- */
.hero {
  position: relative;
  display: grid;
  grid-template-columns: 1fr 1.05fr;
  gap: 56px;
  align-items: center;
  min-height: calc(100vh - 64px);
}

/* Hero 顶部克制辉光：单一强调色的极淡径向渐变 */
.hero::before {
  content: "";
  position: absolute;
  top: -120px;
  left: 50%;
  transform: translateX(-50%);
  width: 820px;
  height: 460px;
  background: radial-gradient(ellipse at center, rgba(45, 212, 191, 0.09), transparent 68%);
  pointer-events: none;
  z-index: -1;
}

.hero-actions {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
  margin: 34px 0 0;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0 22px;
  border: 0;
  border-radius: 12px;
  cursor: pointer;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 15px;
  letter-spacing: 0.01em;
  transition: transform 0.18s var(--ease), background 0.2s ease, box-shadow 0.2s ease;
}

.button:hover {
  transform: translateY(-1px);
}

.button:active {
  transform: translateY(0);
}

.button-primary {
  color: var(--on-accent);
  background: var(--accent);
}

.button-primary:hover {
  box-shadow: 0 8px 24px -12px rgba(45, 212, 191, 0.55);
}

.button-secondary {
  color: var(--text);
  background: var(--panel-2);
  border: 1px solid var(--line-strong);
}

.button-secondary:hover {
  background: var(--panel-3);
}

.trust-row {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-top: 26px;
  color: var(--text-3);
  font-size: 13px;
}

.trust-row span {
  padding: 7px 12px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(17, 17, 20, 0.6);
}

/* ---------- 卡片通用 ---------- */
.hero-video-card,
.generator-form,
.price-card,
.feature-card,
.quote-card,
.metrics-band,
.steps article {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
}

/* ---------- 视频 ---------- */
.hero-video-card {
  padding: 12px;
  background: linear-gradient(180deg, var(--panel-2), var(--panel));
}

.video-frame {
  position: relative;
  overflow: hidden;
  border-radius: var(--radius);
  background: #0c0c0f;
  aspect-ratio: 16 / 9;
  border: 1px solid var(--line-accent);
}

.video-frame video {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.video-meta {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  padding: 12px 6px 2px;
  color: var(--text-3);
  font-size: 12.5px;
}

/* ---------- 核心能力（Zig-Zag 非对称） ---------- */
.split-section {
  display: grid;
  grid-template-columns: 0.82fr 1.18fr;
  gap: 56px;
  align-items: start;
}

.capability-grid {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 16px;
}

.feature-card {
  padding: 26px;
  grid-column: span 3;
  transition: border-color 0.2s ease, transform 0.2s var(--ease);
}

.large-card {
  grid-column: span 4;
}

.offset-card {
  grid-column: 3 / span 4;
  transform: translateY(18px);
}

.feature-card:hover {
  border-color: var(--line-strong);
  transform: translateY(-2px);
}

.offset-card:hover {
  transform: translateY(16px);
}

.feature-card svg {
  width: 22px;
  height: 22px;
  fill: var(--accent);
}

.feature-card h3,
.steps h3,
.price-card h3 {
  margin: 16px 0 8px;
  color: var(--text-hi);
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 18px;
  letter-spacing: -0.01em;
}

.feature-card p,
.steps p,
.quote-card p,
.price-card p {
  margin: 0;
  color: var(--text-2);
  font-size: 14.5px;
  line-height: 1.7;
}

/* ---------- 调用流程 ---------- */
.workflow {
  text-align: center;
}

.steps {
  display: grid;
  grid-template-columns: 1fr 1.12fr 1fr;
  gap: 16px;
  margin-top: 32px;
  text-align: left;
}

.steps article {
  padding: 30px 28px;
  position: relative;
}

.steps span {
  color: var(--accent);
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 14px;
  letter-spacing: 0.08em;
}

.steps article::before {
  content: "";
  position: absolute;
  top: 0;
  left: 28px;
  width: 34px;
  height: 2px;
  background: linear-gradient(90deg, var(--accent-mid), transparent);
}

/* ---------- 实力背书 ---------- */
.proof {
  padding-top: 40px;
}

.metrics-band {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0;
  padding: 6px 26px;
  margin-bottom: 40px;
}

.metrics-band div {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 22px 18px;
  border-right: 1px solid var(--line);
}

.metrics-band div:last-child {
  border-right: 0;
}

.metrics-band strong {
  font-family: var(--font-display);
  font-size: 32px;
  font-weight: 600;
  letter-spacing: -0.02em;
  color: var(--text-hi);
  font-variant-numeric: tabular-nums;
}

.metrics-band span {
  font-size: 13px;
  color: var(--text-3);
}

.case-layout {
  display: grid;
  grid-template-columns: 1fr 0.88fr 0.88fr;
  gap: 16px;
  align-items: stretch;
}

.quote-card {
  padding: 26px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.quote-card span {
  display: block;
  margin-top: 18px;
  color: var(--accent);
  font-size: 13px;
  font-weight: 500;
}

/* ---------- 生成器 ---------- */
.generator {
  display: grid;
  grid-template-columns: 0.72fr 1.28fr;
  gap: 52px;
  align-items: start;
}

.generator-form {
  padding: 28px;
}

.generator-form label {
  display: block;
  margin-bottom: 10px;
  color: var(--text-hi);
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 14px;
}

.generator-form textarea,
.generator-form select {
  width: 100%;
  color: var(--text);
  background: #0c0c0f;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  padding: 14px 16px;
  outline: none;
  transition: border-color 0.2s ease;
}

.generator-form textarea {
  resize: vertical;
  line-height: 1.7;
}

.generator-form textarea:focus,
.generator-form select:focus {
  border-color: var(--accent-mid);
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin: 18px 0;
}

.task-output {
  display: block;
  margin-top: 18px;
  padding: 14px 16px;
  border-radius: var(--radius);
  color: var(--accent);
  font-size: 14px;
  background: var(--accent-soft);
  border: 1px solid var(--line-accent);
}

/* ---------- 定价 ---------- */
.pricing {
  text-align: center;
}

.pricing-grid {
  display: grid;
  grid-template-columns: 0.95fr 1.1fr 0.95fr;
  gap: 16px;
  align-items: center;
  margin-top: 34px;
  text-align: left;
}

.price-card {
  padding: 30px 28px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  transition: border-color 0.2s ease, transform 0.2s var(--ease);
}

.price-card:hover {
  border-color: var(--line-strong);
}

.price-card .plan {
  color: var(--text-3);
  font-family: var(--font-display);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.price-card h3 {
  margin: 0;
  font-size: 26px;
  font-weight: 700;
  letter-spacing: -0.02em;
  font-variant-numeric: tabular-nums;
}

.price-card p {
  font-size: 14px;
  line-height: 1.75;
}

.price-card .button {
  margin-top: 8px;
}

.price-card.featured {
  border-color: var(--line-accent);
  background: linear-gradient(180deg, rgba(15, 23, 42, 0.5), var(--panel));
  transform: translateY(-14px);
  box-shadow: 0 20px 40px -28px rgba(45, 212, 191, 0.35);
}

.price-card.featured .plan {
  color: var(--accent);
}

.plan-feedback {
  margin-top: 26px;
  color: var(--text-3);
  font-size: 14px;
}

/* ---------- FAQ ---------- */
.faq-list {
  display: grid;
  gap: 12px;
  margin-top: 32px;
}

details {
  padding: 20px 24px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  transition: border-color 0.2s ease;
}

details[open] {
  border-color: var(--line-strong);
}

summary {
  cursor: pointer;
  color: var(--text-hi);
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 15.5px;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

summary::-webkit-details-marker {
  display: none;
}

summary::after {
  content: "+";
  color: var(--text-3);
  font-size: 20px;
  font-weight: 400;
  line-height: 1;
  transition: transform 0.22s var(--ease);
}

details[open] summary::after {
  transform: rotate(45deg);
  color: var(--accent);
}

details p {
  margin: 12px 0 0;
  color: var(--text-2);
  font-size: 14.5px;
  line-height: 1.75;
}

/* ---------- Final CTA ---------- */
.final-cta {
  text-align: center;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  background: linear-gradient(180deg, rgba(9, 9, 11, 0.4), rgba(9, 9, 11, 0.4));
}

.final-cta h2 {
  margin-bottom: 14px;
}

.final-cta p {
  color: var(--text-2);
  margin-bottom: 30px;
}

/* ---------- Footer ---------- */
.footer {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  flex-wrap: wrap;
  padding: 30px clamp(18px, 4vw, 60px);
  color: var(--text-3);
  font-size: 13.5px;
  border-top: 1px solid var(--line);
}

.footer span:first-child {
  font-family: var(--font-display);
  font-weight: 600;
  color: var(--text-2);
}

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

/* ---------- 响应式 ---------- */
@media (max-width: 860px) {
  .site-header {
    padding: 14px 18px;
  }

  .menu-toggle {
    display: flex;
  }

  .nav {
    position: absolute;
    top: 64px;
    left: 18px;
    right: 18px;
    display: none;
    flex-direction: column;
    align-items: flex-start;
    gap: 18px;
    padding: 20px;
    border: 1px solid var(--line-strong);
    border-radius: var(--radius-lg);
    background: var(--panel-2);
    box-shadow: 0 24px 48px -24px rgba(0, 0, 0, 0.6);
  }

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

  .header-cta {
    display: none;
  }

  .hero,
  .split-section,
  .generator,
  .case-layout {
    grid-template-columns: 1fr;
  }

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

  .hero {
    min-height: auto;
    gap: 40px;
  }

  .capability-grid,
  .steps,
  .metrics-band,
  .pricing-grid {
    grid-template-columns: 1fr;
  }

  .feature-card,
  .large-card,
  .offset-card {
    grid-column: auto;
    transform: none !important;
  }

  .metrics-band div {
    border-right: 0;
    padding: 18px 0;
    border-bottom: 1px solid var(--line);
  }

  .metrics-band div:last-child {
    border-bottom: 0;
  }

  .price-card.featured {
    transform: none;
  }

  .form-row {
    grid-template-columns: 1fr;
  }

  .video-meta {
    flex-direction: column;
  }

  .hero h1 {
    font-size: 38px;
  }
}