/* ============================================================
   夜色AI - 样式表
   主题:深色夜空(深紫蓝+月光金点缀)
   设计:移动优先,简洁高效
   ============================================================ */

/* ---------- Variables ---------- */
:root {
  --c-primary: #7c5cff;
  --c-primary-dark: #6344e6;
  --c-accent: #ff6b9d;
  --c-purple: #a855f7;
  --c-gold: #ffd470;
  --grad-main: linear-gradient(135deg, #7c5cff 0%, #a855f7 100%);
  --grad-cta: linear-gradient(135deg, #7c5cff 0%, #ff6b9d 100%);
  --grad-gold: linear-gradient(135deg, #ffd470 0%, #ff9d6b 100%);
  --c-text: #1a1430;
  --c-text-soft: #5b5470;
  --c-text-mute: #8a839f;
  --c-bg: #faf9ff;
  --c-bg-alt: #f3f1ff;
  --c-card: #ffffff;
  --c-border: #ece9f7;
  --radius: 16px;
  --radius-sm: 10px;
  --shadow-sm: 0 2px 10px rgba(124, 92, 255, 0.06);
  --shadow: 0 8px 28px rgba(124, 92, 255, 0.12);
  --shadow-lg: 0 18px 50px rgba(124, 92, 255, 0.18);
  --maxw: 1160px;
  --header-h: 60px;
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; scroll-padding-top: var(--header-h); -webkit-text-size-adjust: 100%; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  font-size: 16px;
  line-height: 1.6;
  color: var(--c-text);
  background: var(--c-bg);
  -webkit-font-smoothing: antialiased;
  overflow-x: clip; /* 用 clip 而非 hidden:不创建滚动容器,避免破坏 sticky header */
  /* 移动端悬浮按钮留出底部空间 */
  padding-bottom: 84px;
}
a { color: var(--c-primary); text-decoration: none; }
a:hover { color: var(--c-primary-dark); text-decoration: underline; }
img { max-width: 100%; height: auto; display: block; }
ul, ol { list-style: none; }
button { font: inherit; cursor: pointer; border: none; background: none; }

/* ---------- Layout ---------- */
.container { width: 100%; max-width: var(--maxw); margin: 0 auto; padding: 0 20px; }
.container-narrow { max-width: 820px; }
.section { padding: 56px 0; }
.section-alt { background: var(--c-bg-alt); }
.section-head { text-align: center; margin-bottom: 36px; }
.section-eyebrow {
  font-size: 13px; letter-spacing: 0.05em; color: var(--c-primary);
  font-weight: 600; margin-bottom: 10px;
}
.section-head h2 { font-size: 26px; font-weight: 800; margin-bottom: 10px; }
.section-desc { color: var(--c-text-soft); font-size: 15px; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 12px 26px; border-radius: 999px;
  font-size: 15px; font-weight: 600; text-decoration: none;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  border: 2px solid transparent;
}
.btn:hover { transform: translateY(-2px); text-decoration: none; }
.btn-primary { background: var(--grad-cta); color: #fff; box-shadow: 0 8px 22px rgba(255, 107, 157, 0.3); }
.btn-primary:hover { color: #fff; box-shadow: 0 12px 30px rgba(255, 107, 157, 0.4); }
.btn-ghost { background: transparent; color: var(--c-text); border-color: var(--c-border); }
.btn-ghost:hover { color: var(--c-primary); border-color: var(--c-primary); }
.btn-sm { padding: 8px 18px; font-size: 14px; }
.btn-lg { padding: 15px 36px; font-size: 17px; }

/* ---------- Header ---------- */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(255, 255, 255, 0.88);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--c-border);
  transition: box-shadow 0.3s ease;
}
.site-header.scrolled { box-shadow: var(--shadow-sm); }
.header-inner { display: flex; align-items: center; justify-content: space-between; height: var(--header-h); }
.brand { display: flex; align-items: center; gap: 9px; color: var(--c-text); }
.brand:hover { text-decoration: none; }
.brand-logo { width: 32px; height: 32px; border-radius: 8px; }
.brand-name { font-size: 20px; font-weight: 800; background: var(--grad-main); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent; }
.main-nav { display: none; gap: 26px; }
.main-nav a { color: var(--c-text-soft); font-size: 15px; font-weight: 500; }
.main-nav a:hover { color: var(--c-primary); text-decoration: none; }
.nav-download { display: inline-flex; }

/* 移动端汉堡按钮(默认隐藏,移动端显示) */
.nav-toggle {
  display: none; flex-direction: column; gap: 5px;
  width: 40px; height: 40px;
  align-items: center; justify-content: center; cursor: pointer;
  background: none; border: none; padding: 0;
}
.nav-toggle span {
  display: block; width: 22px; height: 2px; background: var(--c-text);
  border-radius: 2px; transition: transform 0.25s ease, opacity 0.25s ease;
}
.nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ---------- Hero ---------- */
.hero {
  position: relative;
  background:
    radial-gradient(1200px 600px at 80% -10%, rgba(168, 85, 247, 0.35), transparent),
    radial-gradient(900px 500px at 10% 10%, rgba(124, 92, 255, 0.4), transparent),
    linear-gradient(160deg, #0f0a2e 0%, #1a1340 45%, #2a1655 100%);
  color: #fff;
  padding: 44px 0 56px;
  overflow: hidden;
}
.hero-inner { display: flex; flex-direction: column; gap: 28px; align-items: center; text-align: center; }

.hero-eyebrow {
  position: relative; overflow: hidden;
  font-size: 13px; letter-spacing: 0.06em; color: #d9cfff;
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(255, 255, 255, 0.18);
  padding: 6px 16px; border-radius: 999px;
  display: inline-block; margin-bottom: 18px;
}
.hero-text h1 {
  font-size: 28px; line-height: 1.35; font-weight: 800;
  letter-spacing: -0.01em; margin-bottom: 16px;
}
.hero-text h1 strong {
  background: linear-gradient(90deg, #a855f7, #ff6b9d, #a855f7);
  background-size: 200% 100%;
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent;
}
.hero-sub { font-size: 15px; color: #d8d2f0; max-width: 560px; margin: 0 auto; }
.hero-sub strong { color: #fff; }
.hero-cta { display: flex; flex-wrap: wrap; gap: 12px; justify-content: center; margin-top: 26px; }
.hero-stats {
  display: flex; gap: 24px; justify-content: center;
  margin-top: 34px; flex-wrap: wrap;
}
.hero-stats dt {
  font-size: 24px; font-weight: 800;
  background: linear-gradient(90deg, #fff, #d9cfff);
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent;
}
.hero-stats dd { font-size: 13px; color: #b9b0e0; }

/* hero 图为竖长手机截图(607×1080),用 height 限制 */
.hero-visual { position: relative; width: 200px; margin: 12px auto 0; }
.hero-visual > img:not(.hero-visual-sub) {
  position: relative; z-index: 2; display: block;
  width: 100%; height: auto;
  border-radius: 22px; box-shadow: 0 20px 60px rgba(0, 0, 0, 0.4);
  animation: floatMain 5s ease-in-out infinite;
  will-change: transform;
}
.hero-visual .hero-visual-sub {
  position: absolute; top: 26px; width: 74%;
  border-radius: 20px; box-shadow: 0 12px 36px rgba(0, 0, 0, 0.3);
  opacity: 0.5; filter: blur(0.5px); z-index: 1; display: none;
}
.hero-visual .hero-visual-sub { left: -12%; animation: floatSubLeft 5s ease-in-out infinite; }
.hero-visual .hero-visual-sub2 { left: auto; right: -12%; animation: floatSubRight 5.5s ease-in-out infinite 0.6s; }

/* ---------- Hero 背景动画 ---------- */
.hero::before,
.hero::after {
  content: ""; position: absolute; border-radius: 50%;
  filter: blur(60px); opacity: 0.5; pointer-events: none; z-index: 0;
}
.hero::before {
  width: 260px; height: 260px;
  background: radial-gradient(circle, rgba(168,85,247,0.7), transparent 70%);
  top: 10%; left: -8%;
  animation: floatOrb 9s ease-in-out infinite;
}
.hero::after {
  width: 220px; height: 220px;
  background: radial-gradient(circle, rgba(255,107,157,0.6), transparent 70%);
  bottom: 6%; right: -6%;
  animation: floatOrb 11s ease-in-out infinite 1.2s;
}
.hero-inner { position: relative; z-index: 1; }
.hero-visual::before {
  content: ""; position: absolute; inset: -8% -6%;
  background: radial-gradient(circle at 50% 45%, rgba(168,85,247,0.55), rgba(124,92,255,0.25) 45%, transparent 70%);
  filter: blur(30px); z-index: 0;
  border-radius: 40% 60% 55% 45% / 50% 45% 55% 50%;
  animation: pulseGlow 3.6s ease-in-out infinite;
}

/* ---------- Keyframes ---------- */
@keyframes floatMain {
  0%, 100% { transform: translateY(0) rotate(0deg); }
  25% { transform: translateY(-12px) rotate(-1deg); }
  50% { transform: translateY(-16px) rotate(0deg); }
  75% { transform: translateY(-8px) rotate(1deg); }
}
@keyframes floatSubLeft {
  0%, 100% { transform: translateY(0) rotate(-6deg); }
  50% { transform: translateY(-10px) rotate(-6deg); }
}
@keyframes floatSubRight {
  0%, 100% { transform: translateY(0) rotate(6deg); }
  50% { transform: translateY(-12px) rotate(6deg); }
}
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(22px); }
  to { opacity: 1; transform: translateY(0); }
}
@keyframes popIn {
  0% { opacity: 0; transform: translateY(18px) scale(0.92); }
  70% { opacity: 1; transform: translateY(0) scale(1.04); }
  100% { opacity: 1; transform: translateY(0) scale(1); }
}
@keyframes floatOrb {
  0%, 100% { transform: translate(0,0) scale(1); }
  50% { transform: translate(20px,-26px) scale(1.08); }
}
@keyframes pulseGlow {
  0%, 100% { opacity: 0.45; transform: scale(1); }
  50% { opacity: 0.85; transform: scale(1.06); }
}
@keyframes gradientShift {
  0% { background-position: 0% 50%; }
  100% { background-position: 200% 50%; }
}
@keyframes shimmer {
  0% { transform: translateX(-120%); }
  100% { transform: translateX(220%); }
}
@keyframes ctaPulse {
  0%, 100% { box-shadow: 0 8px 24px rgba(124,92,255,0.45), 0 0 0 0 rgba(124,92,255,0.5); }
  50% { box-shadow: 0 10px 30px rgba(124,92,255,0.6), 0 0 0 10px rgba(124,92,255,0); }
}

/* ---------- Hero 动画应用 ---------- */
.hero-eyebrow { animation: fadeInUp 0.7s ease-out 0.10s both; }
.hero-eyebrow::after {
  content: ""; position: absolute; top: 0; left: 0; bottom: 0; width: 40%;
  background: linear-gradient(100deg, transparent, rgba(255,255,255,0.55), transparent);
  animation: shimmer 4.5s ease-in-out infinite 1s;
}
.hero-text h1 { animation: fadeInUp 0.7s ease-out 0.20s both; }
.hero-text h1 strong { animation: gradientShift 4s linear infinite; }
.hero-sub { animation: fadeInUp 0.7s ease-out 0.30s both; }
.hero-cta { animation: fadeInUp 0.7s ease-out 0.40s both; }
.hero-cta .btn-primary { animation: ctaPulse 2.6s ease-in-out infinite 0.8s; }
.hero-stats { animation: fadeInUp 0.7s ease-out 0.50s both; }
.hero-stats > div { animation: popIn 0.6s cubic-bezier(.34,1.56,.64,1) both; }
.hero-stats > div:nth-child(1) { animation-delay: 0.50s; }
.hero-stats > div:nth-child(2) { animation-delay: 0.64s; }
.hero-stats > div:nth-child(3) { animation-delay: 0.78s; }
.hero-stats > div:nth-child(4) { animation-delay: 0.92s; }
.hero-visual { animation: fadeInUp 0.8s ease-out 0.35s both; }
.hero-visual .hero-visual-sub { animation: floatSubLeft 5s ease-in-out infinite; }
.hero-visual .hero-visual-sub2 { animation: floatSubRight 5.5s ease-in-out infinite 0.6s; }

/* ---------- Features ---------- */
.feature-grid { display: grid; grid-template-columns: 1fr; gap: 16px; }
.feature-card {
  background: var(--c-card); border: 1px solid var(--c-border);
  border-radius: var(--radius); padding: 26px 22px; box-shadow: var(--shadow-sm);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.feature-card:hover { transform: translateY(-4px); box-shadow: var(--shadow); }
.feature-icon {
  width: 48px; height: 48px; border-radius: 12px;
  background: linear-gradient(135deg, rgba(124,92,255,0.1), rgba(168,85,247,0.1));
  color: var(--c-primary); display: flex; align-items: center; justify-content: center;
  margin-bottom: 14px;
}
.feature-card h3 { font-size: 17px; font-weight: 700; margin-bottom: 8px; }
.feature-card p { font-size: 14px; color: var(--c-text-soft); line-height: 1.65; }

/* ---------- Scenes ---------- */
.scene-list { display: grid; grid-template-columns: 1fr; gap: 20px; }
.scene-card {
  background: var(--c-card); border-radius: var(--radius);
  overflow: hidden; box-shadow: var(--shadow-sm);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.scene-card:hover { transform: translateY(-4px); box-shadow: var(--shadow); }
.scene-card img { width: 100%; aspect-ratio: 607/1080; object-fit: cover; max-height: 340px; }
.scene-body { padding: 22px; }
.scene-body h3 { font-size: 18px; font-weight: 700; margin-bottom: 8px; }
.scene-body p { font-size: 14px; color: var(--c-text-soft); line-height: 1.7; }

/* ---------- Preview ---------- */
.preview-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 14px; }
.preview-card { text-align: center; }
.preview-card img {
  width: 100%; aspect-ratio: 607/1080; object-fit: cover;
  border-radius: var(--radius); box-shadow: var(--shadow);
  transition: transform 0.2s ease;
}
.preview-card:hover img { transform: translateY(-4px); }
.preview-card figcaption { font-size: 13px; color: var(--c-text-soft); margin-top: 8px; }

/* ---------- Demo ---------- */
.demo-inner { display: flex; flex-direction: column; gap: 32px; }
.demo-text h2 { font-size: 24px; font-weight: 800; margin-bottom: 10px; }
.demo-desc { color: var(--c-text-soft); margin-bottom: 22px; font-size: 15px; }
.chat-demo { display: flex; flex-direction: column; gap: 14px; }
.bubble {
  display: flex; gap: 10px; max-width: 88%;
  animation: fadeInUp 0.5s ease-out both;
}
.bubble-ai { align-self: flex-start; }
.bubble-user { align-self: flex-end; flex-direction: row-reverse; }
.bubble-avatar {
  width: 36px; height: 36px; border-radius: 50%; flex-shrink: 0;
  background: var(--grad-main); color: #fff; font-size: 14px; font-weight: 700;
  display: flex; align-items: center; justify-content: center;
}
.bubble p {
  padding: 12px 16px; border-radius: 16px; font-size: 14px; line-height: 1.6;
}
.bubble-ai p { background: var(--c-card); border: 1px solid var(--c-border); border-top-left-radius: 4px; }
.bubble-user p { background: var(--grad-cta); color: #fff; border-top-right-radius: 4px; }
.bubble:nth-child(1) { animation-delay: 0.1s; }
.bubble:nth-child(2) { animation-delay: 0.3s; }
.bubble:nth-child(3) { animation-delay: 0.5s; }
.demo-visual { display: none; }
.demo-visual img { width: 100%; border-radius: var(--radius); box-shadow: var(--shadow-lg); }

/* ---------- Compare Table ---------- */
.compare-table-wrap { overflow-x: auto; -webkit-overflow-scrolling: touch; }
.compare-table {
  width: 100%; border-collapse: collapse;
  background: var(--c-card); border-radius: var(--radius);
  overflow: hidden; box-shadow: var(--shadow-sm);
  min-width: 480px;
}
.compare-table th, .compare-table td { padding: 14px 16px; text-align: left; font-size: 14px; }
.compare-table thead { background: var(--c-bg-alt); }
.compare-table th { font-weight: 700; font-size: 15px; }
.compare-table th.col-yese { color: var(--c-primary); }
.compare-table tbody tr { border-top: 1px solid var(--c-border); }
.compare-table td.col-yese { color: var(--c-primary); font-weight: 600; }
.compare-table td:not(.col-yese) { color: var(--c-text-mute); }

/* ---------- Reviews ---------- */
.review-grid { display: grid; grid-template-columns: 1fr; gap: 16px; }
.review-card {
  background: var(--c-card); border-radius: var(--radius);
  padding: 24px 22px; box-shadow: var(--shadow-sm);
  display: flex; flex-direction: column; gap: 12px;
}
.review-avatar {
  width: 44px; height: 44px; border-radius: 50%; flex-shrink: 0;
  background: var(--av-color, var(--c-primary)); color: #fff;
  font-size: 18px; font-weight: 700;
  display: flex; align-items: center; justify-content: center;
}
.review-card blockquote p { font-size: 14px; line-height: 1.7; color: var(--c-text); }
.review-card figcaption { font-size: 13px; color: var(--c-text-mute); }
.review-card figcaption strong { color: var(--c-text); }

/* ---------- Timeline ---------- */
.timeline { position: relative; padding-left: 28px; }
.timeline::before {
  content: ""; position: absolute; left: 6px; top: 4px; bottom: 4px;
  width: 2px; background: linear-gradient(to bottom, var(--c-primary), var(--c-accent));
}
.timeline-item { position: relative; padding-bottom: 26px; }
.timeline-item:last-child { padding-bottom: 0; }
.timeline-item::before {
  content: ""; position: absolute; left: -28px; top: 4px;
  width: 14px; height: 14px; border-radius: 50%;
  background: var(--c-primary); border: 3px solid var(--c-bg);
}
.timeline-date { font-size: 13px; color: var(--c-primary); font-weight: 600; }
.timeline-body h3 { font-size: 16px; font-weight: 700; margin: 4px 0 6px; }
.timeline-body p { font-size: 14px; color: var(--c-text-soft); }

/* ---------- FAQ ---------- */
.faq-list { display: flex; flex-direction: column; gap: 12px; }
.faq-item {
  background: var(--c-card); border: 1px solid var(--c-border);
  border-radius: var(--radius-sm); overflow: hidden;
}
.faq-item summary {
  padding: 16px 20px; font-size: 15px; font-weight: 600;
  cursor: pointer; list-style: none; position: relative;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: "+"; position: absolute; right: 20px; top: 50%; transform: translateY(-50%);
  font-size: 20px; color: var(--c-primary); transition: transform 0.2s;
}
.faq-item[open] summary::after { transform: translateY(-50%) rotate(45deg); }
.faq-answer { padding: 0 20px 16px; font-size: 14px; color: var(--c-text-soft); line-height: 1.7; }
.faq-answer strong { color: var(--c-text); }

/* ---------- Characters (角色展示) ---------- */
.character-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 16px; }
.character-card {
  background: var(--c-card); border: 1px solid var(--c-border);
  border-radius: var(--radius); padding: 22px 18px; box-shadow: var(--shadow-sm);
  text-align: center; display: flex; flex-direction: column; align-items: center;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.character-card:hover { transform: translateY(-4px); box-shadow: var(--shadow); }
.character-avatar {
  width: 56px; height: 56px; border-radius: 50%; flex-shrink: 0;
  background: var(--av-color, var(--c-primary)); color: #fff;
  font-size: 22px; font-weight: 700;
  display: flex; align-items: center; justify-content: center;
  margin-bottom: 12px;
}
.character-card h3 { font-size: 16px; font-weight: 700; margin-bottom: 6px; }
.character-tag {
  display: inline-block; font-size: 12px; font-weight: 600;
  color: var(--c-primary); background: rgba(124, 92, 255, 0.1);
  padding: 3px 12px; border-radius: 999px; margin-bottom: 10px;
}
.character-card p { font-size: 13px; color: var(--c-text-soft); line-height: 1.6; }
.character-note {
  text-align: center; margin-top: 22px; font-size: 14px;
  color: var(--c-text-soft); max-width: 720px; margin-left: auto; margin-right: auto;
}
.character-note strong { color: var(--c-primary); }

/* ---------- Tutorial (使用教程) ---------- */
.tutorial-list { display: grid; grid-template-columns: 1fr; gap: 16px; }
.tutorial-step {
  background: var(--c-card); border: 1px solid var(--c-border);
  border-radius: var(--radius); padding: 22px 20px; box-shadow: var(--shadow-sm);
  display: flex; gap: 16px; align-items: flex-start;
}
.tutorial-num {
  flex-shrink: 0; width: 40px; height: 40px; border-radius: 50%;
  background: var(--grad-cta); color: #fff; font-size: 18px; font-weight: 700;
  display: flex; align-items: center; justify-content: center;
}
.tutorial-body h3 { font-size: 16px; font-weight: 700; margin-bottom: 6px; }
.tutorial-body p { font-size: 14px; color: var(--c-text-soft); line-height: 1.7; }

/* ---------- Download ---------- */
.download-cta {
  background: linear-gradient(160deg, #1a1340 0%, #2a1655 100%);
  color: #fff;
}
.download-inner { text-align: center; }
.download-text .section-eyebrow { color: var(--c-gold); }
.download-text h2 { font-size: 26px; font-weight: 800; margin-bottom: 10px; }
.download-desc { color: #d8d2f0; max-width: 560px; margin: 0 auto; font-size: 15px; }
.download-meta {
  display: flex; flex-wrap: wrap; gap: 8px 18px; justify-content: center;
  font-size: 14px; color: #b9b0e0; margin: 18px 0 26px;
}
.download-meta li { list-style: none; }
.download-actions { display: flex; flex-direction: column; align-items: center; gap: 10px; }

/* ---------- Footer ---------- */
.site-footer { background: #0f0a2e; color: #b9b0e0; padding: 40px 0 24px; }
.footer-inner { display: flex; flex-direction: column; gap: 24px; align-items: flex-start; }
.footer-brand { display: flex; gap: 14px; align-items: center; }
.footer-brand img { width: 40px; height: 40px; border-radius: 8px; }
.footer-brand strong { display: block; color: #fff; font-size: 16px; }
.footer-brand p { font-size: 13px; max-width: 320px; }
.footer-nav { display: flex; flex-wrap: wrap; gap: 16px 22px; }
.footer-nav a { color: #b9b0e0; font-size: 14px; }
.footer-nav a:hover { color: #fff; text-decoration: none; }
.footer-bottom { border-top: 1px solid rgba(255, 255, 255, 0.1); margin-top: 26px; padding-top: 18px; text-align: center; }
.footer-bottom p { font-size: 12px; color: #8a83a8; margin-bottom: 4px; }
.footer-icp a { color: #8a83a8; text-decoration: none; }
.footer-icp a:hover { color: #b9b0e0; text-decoration: underline; }

/* ---------- Floating download (mobile) ---------- */
.float-download {
  position: fixed; bottom: calc(16px + env(safe-area-inset-bottom));
  left: 16px; right: 16px;
  background: var(--grad-cta); color: #fff; text-align: center;
  padding: 15px; border-radius: 999px; font-weight: 700; font-size: 16px;
  box-shadow: 0 10px 30px rgba(255, 107, 157, 0.4);
  z-index: 90; transition: transform 0.2s ease, opacity 0.2s ease;
}
.float-download:hover { text-decoration: none; transform: translateY(-2px); }
.float-download.hidden { opacity: 0; pointer-events: none; transform: translateY(20px); }

/* ============================================================
   Responsive — Mobile nav dropdown (<960px)
   ============================================================ */
@media (max-width: 959px) {
  .nav-toggle { display: flex; }
  /* 移动端隐藏头部下载按钮,由底部悬浮按钮承担 CTA,避免拥挤 */
  .nav-download { display: none; }
  .main-nav {
    position: absolute; top: var(--header-h); left: 0; right: 0;
    flex-direction: column; gap: 0;
    background: #fff; padding: 6px 20px;
    box-shadow: var(--shadow); border-top: 1px solid var(--c-border);
    display: none;
  }
  .main-nav.open { display: flex; }
  .main-nav a { padding: 14px 0; border-bottom: 1px solid var(--c-border); width: 100%; }
  .main-nav a:last-child { border-bottom: none; }
}

/* ============================================================
   Responsive — Tablet (≥640px)
   ============================================================ */
@media (min-width: 640px) {
  .section { padding: 72px 0; }
  .section-head h2 { font-size: 30px; }
  .hero { padding: 64px 0 80px; }
  .hero-text h1 { font-size: 36px; }
  .hero-sub { font-size: 16px; }
  .feature-grid { grid-template-columns: repeat(2, 1fr); gap: 20px; }
  .scene-list { grid-template-columns: repeat(2, 1fr); }
  .review-grid { grid-template-columns: repeat(2, 1fr); }
  .preview-grid { grid-template-columns: repeat(3, 1fr); }
  .character-grid { grid-template-columns: repeat(3, 1fr); gap: 18px; }
  .tutorial-list { grid-template-columns: repeat(2, 1fr); gap: 18px; }
  .hero-visual { width: 250px; }
  .float-download { left: auto; right: 24px; bottom: 24px; width: auto; padding: 14px 28px; }
}

/* ============================================================
   Responsive — Desktop (≥960px)
   ============================================================ */
@media (min-width: 960px) {
  body { padding-bottom: 0; }
  .main-nav { display: flex; }
  .container { padding: 0 32px; }
  .section { padding: 96px 0; }
  .section-head h2 { font-size: 34px; }
  .section-head { margin-bottom: 52px; }

  .hero-inner { flex-direction: row; text-align: left; gap: 48px; }
  .hero-text { flex: 1; }
  .hero-text h1 { font-size: 44px; }
  .hero-sub { margin: 0; max-width: none; }
  .hero-cta { justify-content: flex-start; }
  .hero-stats { justify-content: flex-start; margin-top: 38px; gap: 36px; }
  .hero-visual { width: auto; height: 480px; margin: 0; flex-shrink: 0; }
  .hero-visual > img:not(.hero-visual-sub) { width: auto; height: 100%; }
  .hero-visual .hero-visual-sub { display: block; width: auto; height: 78%; }

  .feature-grid { grid-template-columns: repeat(3, 1fr); gap: 24px; }
  .scene-list { grid-template-columns: repeat(3, 1fr); }
  .review-grid { grid-template-columns: repeat(3, 1fr); }
  .character-grid { grid-template-columns: repeat(3, 1fr); gap: 22px; }
  .tutorial-list { grid-template-columns: repeat(4, 1fr); gap: 20px; }

  .demo-inner { grid-template-columns: 1.1fr 0.9fr; gap: 48px; display: grid; }
  .demo-visual { display: block; }
  .demo-text h2 { font-size: 28px; }

  .download-text h2 { font-size: 32px; }
  .footer-inner { flex-direction: row; justify-content: space-between; align-items: center; }
  .float-download { display: none; }
}

/* ---------- Motion preference ---------- */
@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; scroll-behavior: auto !important; }
  /* hero 核心循环动效为用户明确要求保留(轻柔浮动,幅度小) */
  .hero-visual > img:not(.hero-visual-sub) { animation: floatMain 5s ease-in-out infinite !important; }
  .hero-visual .hero-visual-sub { animation: floatSubLeft 5s ease-in-out infinite !important; }
  .hero-visual .hero-visual-sub2 { animation: floatSubRight 5.5s ease-in-out infinite 0.6s !important; }
  .hero-cta .btn-primary { animation: ctaPulse 2.6s ease-in-out infinite 0.8s !important; }
}