/* =========================================================
   夜色AI 全站样式表
   主题：深紫黑底 + 紫罗兰星辉（暗夜浪漫风）
   ========================================================= */
:root {
  --violet: #9662F1;
  --violet-deep: #673AB7;
  --violet-light: #B08AF7;
  --violet-soft: #C4A5F9;
  --violet-glow: #D8B4FE;
  --pink-violet: #E879F9;
  --neon-violet: #9333EA;
  --bg-primary: #1A0F2E;
  --bg-deep: #0F0820;
  --bg-card: #241638;
  --bg-card-hover: #2F1F4A;
  --text-primary: #F5F3FF;
  --text-secondary: #A89CC4;
  --text-muted: #6F6589;
  --border-soft: rgba(150, 98, 241, 0.12);
  --border-medium: rgba(150, 98, 241, 0.25);
  --border-strong: rgba(150, 98, 241, 0.45);
  --shadow-sm: 0 4px 12px rgba(0, 0, 0, 0.35);
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.45);
  --shadow-glow: 0 8px 32px rgba(150, 98, 241, 0.55);
  --shadow-card: 0 6px 24px rgba(15, 8, 32, 0.55);
  --gradient-primary: linear-gradient(277deg, #9662F1 8%, #673AB7 96%);
  --gradient-hero: radial-gradient(ellipse at 50% 30%, rgba(150, 98, 241, 0.25) 0%, #1A0F2E 60%, #0F0820 100%);
  --gradient-text: linear-gradient(135deg, #C4A5F9 0%, #E879F9 50%, #9662F1 100%);
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-pill: 999px;
  --container-max: 1200px;
  --container-padding: 24px;
  --font-family: "Inter", "Noto Sans SC", -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", sans-serif;
  --transition-fast: 0.2s ease;
  --transition-base: 0.3s ease;
  --transition-slow: 0.5s ease;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  font-family: var(--font-family);
  font-size: 16px;
  line-height: 1.7;
  color: var(--text-primary);
  background-color: var(--bg-deep);
  background-image: var(--gradient-hero);
  background-attachment: fixed;
  background-size: cover;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
  min-height: 100vh;
}
a { color: inherit; text-decoration: none; transition: color var(--transition-fast); }
a:hover { color: var(--violet-light); }
img { max-width: 100%; height: auto; display: block; }
button { font-family: inherit; cursor: pointer; border: none; background: none; color: inherit; }
ul, ol { list-style: none; }

/* ---------- 装饰背景：星点 + 光斑 ---------- */
.ys-starfield {
  position: fixed;
  inset: 0;
  z-index: -2;
  pointer-events: none;
  overflow: hidden;
}
.ys-starfield::before,
.ys-starfield::after {
  content: "";
  position: absolute;
  width: 600px;
  height: 600px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(216, 180, 254, 0.2) 0%, transparent 70%);
  filter: blur(40px);
  pointer-events: none;
}
.ys-starfield::before { top: -150px; left: -100px; }
.ys-starfield::after {
  bottom: -200px;
  right: -150px;
  background: radial-gradient(circle, rgba(232, 121, 249, 0.18) 0%, transparent 70%);
}
.ys-star {
  position: absolute;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.6);
}
.ys-star.ys-purple {
  background: rgba(216, 180, 254, 0.7);
}


/* ---------- 通用容器 / 区块 ---------- */
.ys-container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding-left: var(--container-padding);
  padding-right: var(--container-padding);
}
section { padding: 96px 0; position: relative; }
.ys-section-head { text-align: center; max-width: 720px; margin: 0 auto 64px; }
.ys-section-eyebrow {
  display: inline-block;
  padding: 6px 16px;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--violet-light);
  background: rgba(150, 98, 241, 0.12);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-pill);
  margin-bottom: 18px;
}
.ys-section-title {
  font-size: clamp(28px, 4vw, 42px);
  line-height: 1.25;
  font-weight: 700;
  margin-bottom: 16px;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: transparent;
}
.ys-section-sub { font-size: 16px; color: var(--text-secondary); line-height: 1.8; }

/* ---------- 按钮 ---------- */
.ys-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 28px;
  font-size: 15px;
  font-weight: 600;
  border-radius: var(--radius-pill);
  border: 1px solid transparent;
  white-space: nowrap;
  cursor: pointer;
  user-select: none;
}
.ys-btn-primary {
  background: var(--gradient-primary);
  color: #fff;
}
.ys-btn-primary:hover {
  color: #fff;
}
.ys-btn-primary:active { }
.ys-btn-ghost {
  background: rgba(255, 255, 255, 0.04);
  color: var(--text-primary);
  border-color: var(--border-medium);
}
.ys-btn-ghost:hover {
  background: rgba(150, 98, 241, 0.12);
  border-color: var(--border-strong);
  color: var(--violet-light);
}
.ys-btn-lg { padding: 18px 36px; font-size: 16px; }
.ys-btn i { font-size: 0.95em; }

/* ---------- 头部导航 ---------- */
.ys-site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(15, 8, 32, 0.75);
  border-bottom: 1px solid var(--border-soft);
}
.ys-site-header.ys-scrolled { background: rgba(15, 8, 32, 0.92); }
.ys-nav {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  height: 72px;
  min-width: 0;
  z-index: 100;
}
.ys-brand {
  position: relative;
  z-index: 2;
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 20px;
  line-height: 1;
  color: var(--text-primary);
  flex-shrink: 0;
  text-decoration: none;
}
.ys-brand:hover { color: var(--violet-light); }
.ys-brand-logo {
  width: 32px;
  height: 32px;
  border-radius: 8px;
  flex-shrink: 0;
}
.ys-brand-name {
  color: var(--violet-light);
  letter-spacing: 0.01em;

}
.ys-nav-menu { display: flex; align-items: center; gap: 8px; }
.ys-nav-menu a {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 14px;
  font-size: 14.5px;
  font-weight: 500;
  color: var(--text-secondary);
  border-radius: var(--radius-pill);
  transition: all var(--transition-fast);
}
.ys-nav-menu a:hover { color: var(--text-primary); background: rgba(150, 98, 241, 0.1); }
.ys-nav-menu a i { font-size: 13px; color: var(--violet-light); }
.ys-nav-actions {
  position: relative;
  z-index: 2;
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

/* 移动端菜单按钮 */
.ys-menu-toggle {
  display: none;
  width: 40px;
  height: 40px;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  color: var(--text-primary);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm);
}
.ys-menu-toggle:hover { background: rgba(150, 98, 241, 0.1); }

/* ---------- Hero 区 ---------- */
.ys-hero {
  position: relative;
  padding: 72px 0 88px;
  overflow: hidden;
  text-align: center;
}
.ys-hero-bg {
  position: absolute;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  overflow: hidden;
}
.ys-hero-glow {
  position: absolute;
  top: 50%;
  left: 50%;
  width: min(820px, 110%);
  aspect-ratio: 1 / 1;
  transform: translate(-50%, -50%);
  background: radial-gradient(circle at 50% 50%, rgba(150, 98, 241, 0.45) 0%, rgba(232, 121, 249, 0.18) 28%, transparent 65%);
  filter: blur(50px);
}

.ys-hero-rings {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 1px;
  height: 1px;
}
.ys-hero-rings span {
  position: absolute;
  top: 50%;
  left: 50%;
  border-radius: 50%;
  border: 1px solid rgba(150, 98, 241, 0.14);
  transform: translate(-50%, -50%);
}
.ys-hero-rings span:nth-child(1) { width: 360px; height: 360px; }
.ys-hero-rings span:nth-child(2) {
  width: 560px;
  height: 560px;
  border-color: rgba(232, 121, 249, 0.1);
}
.ys-hero-rings span:nth-child(3) {
  width: 760px;
  height: 760px;
  border-color: rgba(216, 180, 254, 0.07);
}

.ys-hero-inner {
  position: relative;
  z-index: 1;
  max-width: 760px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
}
.ys-hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  font-size: 12.5px;
  font-weight: 600;
  color: var(--violet-light);
  background: rgba(150, 98, 241, 0.12);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-pill);
  margin-bottom: 18px;
}
.ys-hero-eyebrow i { font-size: 11px; }
.ys-hero-title {
  font-size: clamp(32px, 5.2vw, 56px);
  line-height: 1.15;
  font-weight: 800;
  margin-bottom: 16px;
  letter-spacing: -0.02em;
}
.ys-hero-title .ys-highlight {
  background: var(--gradient-text);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
.ys-hero-sub {
  font-size: clamp(15px, 1.3vw, 17px);
  color: var(--text-secondary);
  line-height: 1.7;
  margin: 0 auto 24px;
  max-width: 620px;
}
.ys-hero-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
  margin-bottom: 24px;
}
.ys-hero-actions .ys-btn-lg { padding: 14px 28px; font-size: 15px; }
.ys-hero-meta {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px 24px;
  color: var(--text-muted);
  font-size: 13.5px;
  margin-bottom: 28px;
}
.ys-hero-meta span { display: inline-flex; align-items: center; gap: 6px;     color: var(--text-secondary);}
.ys-hero-meta i { color: var(--violet-light); font-size: 12px; }

.ys-hero-trust {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  padding: 6px 18px 6px 8px;
  background: rgba(36, 22, 56, 0.55);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-pill);
}
.ys-hero-trust-avatars { display: inline-flex; align-items: center; }
.ys-hero-trust-avatars span {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 11px;
  font-weight: 700;
  color: #fff;
  border: 2px solid var(--bg-deep);
  margin-left: -8px;
  flex-shrink: 0;
}
.ys-hero-trust-avatars span:first-child { margin-left: 0; }
.ys-hero-trust-avatars span:nth-child(1) { background: linear-gradient(135deg, #9662F1, #E879F9); }
.ys-hero-trust-avatars span:nth-child(2) { background: linear-gradient(135deg, #673AB7, #9333EA); }
.ys-hero-trust-avatars span:nth-child(3) { background: linear-gradient(135deg, #C4A5F9, #9662F1); }
.ys-hero-trust-avatars span:nth-child(4) { background: linear-gradient(135deg, #E879F9, #B08AF7); }
.ys-hero-trust-avatars span:nth-child(5) { background: rgba(150, 98, 241, 0.18); color: var(--violet-light); font-size: 12px; }
.ys-hero-trust-text { font-size: 13px; color: var(--text-secondary); font-weight: 500; white-space: nowrap; }
.ys-hero-trust-text strong { color: var(--text-primary); font-weight: 700; }

/* ---------- Features 核心特色 ---------- */
.ys-features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
.ys-feature-card {
  position: relative;
  padding: 32px 28px;
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-lg);
  overflow: hidden;
}
.ys-feature-card:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-strong);
}
.ys-feature-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 56px;
  height: 56px;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, rgba(150, 98, 241, 0.2), rgba(103, 58, 183, 0.1));
  border: 1px solid var(--border-soft);
  margin-bottom: 20px;
  font-size: 22px;
  color: var(--violet-light);
}
.ys-feature-title {
  font-size: 18px;
  font-weight: 700;
  margin-bottom: 10px;
  color: var(--text-primary);
}
.ys-feature-desc {
  font-size: 14.5px;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* ---------- Scenes 使用场景 ---------- */
.ys-scenes-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}
.ys-scene-card {
  position: relative;
  padding: 32px 24px;
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-lg);
  text-align: center;
  overflow: hidden;
}
.ys-scene-card:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-strong);
}
.ys-scene-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: linear-gradient(135deg, rgba(232, 121, 249, 0.15), rgba(150, 98, 241, 0.1));
  border: 1px solid var(--border-soft);
  margin-bottom: 20px;
  font-size: 20px;
  color: var(--pink-violet);
}
.ys-scene-title {
  font-size: 17px;
  font-weight: 700;
  margin-bottom: 10px;
  color: var(--text-primary);
}
.ys-scene-desc {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* ---------- Gallery 角色画廊 ---------- */
.ys-gallery-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
.ys-gallery-card {
  position: relative;
  padding: 32px 24px 24px;
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-lg);
  text-align: center;
  overflow: hidden;
}
.ys-gallery-card:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-strong);
}
.ys-gallery-avatar {
  width: 72px;
  height: 72px;
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  font-weight: 800;
  color: #fff;
  margin-bottom: 16px;
  border: 2px solid rgba(255, 255, 255, 0.15);
}
.ys-gallery-avatar.ys-g1 { background: linear-gradient(135deg, #C4A5F9, #9662F1); }
.ys-gallery-avatar.ys-g2 { background: linear-gradient(135deg, #673AB7, #4A148C); }
.ys-gallery-avatar.ys-g3 { background: linear-gradient(135deg, #E879F9, #D946EF); }
.ys-gallery-avatar.ys-g4 { background: linear-gradient(135deg, #9333EA, #6B21A8); }
.ys-gallery-avatar.ys-g5 { background: linear-gradient(135deg, #4A148C, #1E1B4B); }
.ys-gallery-avatar.ys-g6 { background: linear-gradient(135deg, #B08AF7, #7C3AED); }
.ys-gallery-avatar.ys-g7 { background: linear-gradient(135deg, #06B6D4, #0891B2); }
.ys-gallery-avatar.ys-g8 { background: linear-gradient(135deg, #F472B6, #EC4899); }
.ys-gallery-avatar.ys-g9 { background: linear-gradient(135deg, #FB923C, #F97316); }
.ys-gallery-name {
  font-size: 18px;
  font-weight: 700;
  margin-bottom: 4px;
  color: var(--text-primary);
}
.ys-gallery-role {
  font-size: 13px;
  color: var(--violet-light);
  margin-bottom: 12px;
}
.ys-gallery-tags {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 6px;
}
.ys-gallery-tag {
  padding: 4px 10px;
  font-size: 12px;
  color: var(--text-secondary);
  background: rgba(150, 98, 241, 0.08);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-pill);
}

/* ---------- Stats 平台数据 ---------- */
.ys-stats-section {
  background: rgba(150, 98, 241, 0.04);
  border-top: 1px solid var(--border-soft);
  border-bottom: 1px solid var(--border-soft);
}
.ys-stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}
.ys-stat-card {
  text-align: center;
  padding: 32px 16px;
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-lg);
}
.ys-stat-card:hover {
  border-color: var(--border-medium);
}
.ys-stat-num {
  font-size: clamp(32px, 4vw, 48px);
  font-weight: 800;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 8px;
  line-height: 1.2;
}
.ys-stat-label {
  font-size: 14px;
  color: var(--text-secondary);
  font-weight: 500;
}

/* ---------- Testimonials 用户评价 ---------- */
.ys-testimonials-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
.ys-testimonial-card {
  padding: 32px 28px;
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-lg);
  position: relative;
}
.ys-testimonial-card:hover {
  border-color: var(--border-medium);
}
.ys-testimonial-quote {
  font-size: 24px;
  color: var(--violet);
  opacity: 0.3;
  margin-bottom: 16px;
}
.ys-testimonial-text {
  font-size: 14.5px;
  color: var(--text-secondary);
  line-height: 1.8;
  margin-bottom: 24px;
  font-style: italic;
}
.ys-testimonial-user {
  display: flex;
  align-items: center;
  gap: 12px;
}
.ys-testimonial-avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 14px;
  font-weight: 700;
  color: #fff;
  flex-shrink: 0;
}
.ys-testimonial-name {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-primary);
}
.ys-testimonial-role {
  font-size: 12.5px;
  color: var(--text-muted);
}

/* ---------- FAQ ---------- */
.ys-faq-list {
  max-width: 760px;
  margin: 0 auto;
}
.ys-faq-item {
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-md);
  margin-bottom: 12px;
  overflow: hidden;
  background: var(--bg-card);
}
.ys-faq-item:hover { border-color: var(--border-medium); }
.ys-faq-item.ys-active { border-color: var(--border-strong); }
.ys-faq-question {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 24px;
  font-size: 15px;
  font-weight: 600;
  color: var(--text-primary);
  text-align: left;
  transition: color var(--transition-fast);
}
.ys-faq-question:hover { color: var(--violet-light); }
.ys-faq-icon {
  font-size: 14px;
  color: var(--violet-light);
  flex-shrink: 0;
  margin-left: 16px;
}
.ys-faq-item.ys-active .ys-faq-icon { }
.ys-faq-answer {
  max-height: 0;
  overflow: hidden;
}
.ys-faq-item.ys-active .ys-faq-answer {
  max-height: 300px;
}
.ys-faq-answer p {
  padding: 0 24px 18px;
  font-size: 14.5px;
  color: var(--text-secondary);
  line-height: 1.8;
}

/* ---------- CTA 区 ---------- */
.ys-cta-section { padding: 80px 0; }
.ys-cta-card {
  text-align: center;
  padding: 64px 40px;
  background: var(--bg-card);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-lg);
  position: relative;
  overflow: hidden;
}

.ys-cta-title {
  font-size: clamp(28px, 4vw, 40px);
  font-weight: 800;
  margin-bottom: 16px;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  position: relative;
}
.ys-cta-sub {
  font-size: 16px;
  color: var(--text-secondary);
  margin-bottom: 32px;
  max-width: 520px;
  margin-left: auto;
  margin-right: auto;
  position: relative;
}
.ys-cta-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
  position: relative;
}

/* ---------- Footer ---------- */
.ys-site-footer {
  padding: 64px 0 0;
  border-top: 1px solid var(--border-soft);
}
.ys-footer-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1fr 1fr;
  gap: 40px;
  padding-bottom: 48px;
}
.ys-footer-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 16px;
}
.ys-footer-desc {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 20px;
}
.ys-footer-social {
  display: flex;
  gap: 10px;
}
.ys-social-icon {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: rgba(150, 98, 241, 0.1);
  border: 1px solid var(--border-soft);
  color: var(--text-secondary);
  font-size: 14px;
  transition: all var(--transition-fast);
}
.ys-social-icon:hover {
  background: rgba(150, 98, 241, 0.2);
  border-color: var(--border-medium);
  color: var(--violet-light);
}
.ys-footer-col h4 {
  font-size: 14px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 16px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.ys-footer-col ul li { margin-bottom: 10px; }
.ys-footer-col ul a {
  font-size: 14px;
  color: var(--text-secondary);
  transition: color var(--transition-fast);
}
.ys-footer-col ul a:hover { color: var(--violet-light); }
.ys-footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px;
  padding: 20px 0;
  border-top: 1px solid var(--border-soft);
}
.ys-footer-copy {
  font-size: 13px;
  color: var(--text-muted);
}
.ys-footer-legal {
  display: flex;
  gap: 20px;
}
.ys-footer-legal a {
  font-size: 13px;
  color: var(--text-muted);
  transition: color var(--transition-fast);
}
.ys-footer-legal a:hover { color: var(--violet-light); }

/* ---------- Back to Top ---------- */
.ys-back-to-top {
  position: fixed;
  bottom: 32px;
  right: 32px;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--gradient-primary);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 16px;
  opacity: 0;
  visibility: hidden;
  z-index: 90;
}
.ys-back-to-top.ys-visible {
  opacity: 1;
  visibility: visible;
}
.ys-back-to-top:hover {
}

/* ---------- 响应式 ---------- */
@media (max-width: 1024px) {
  .ys-features-grid { grid-template-columns: repeat(2, 1fr); }
  .ys-scenes-grid { grid-template-columns: repeat(2, 1fr); }
  .ys-gallery-grid { grid-template-columns: repeat(3, 1fr); }
  .ys-stats-grid { grid-template-columns: repeat(2, 1fr); }
  .ys-testimonials-grid { grid-template-columns: repeat(2, 1fr); }
  .ys-footer-grid { grid-template-columns: repeat(3, 1fr); }
}
@media (max-width: 768px) {
  .ys-nav-menu { display: none; }
  .ys-menu-toggle { display: inline-flex; }
  .ys-nav-menu.ys-open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 72px;
    left: 0;
    right: 0;
    background: var(--bg-card);
    border-bottom: 1px solid var(--border-medium);
    padding: 16px;
    gap: 4px;
  }
  .ys-features-grid { grid-template-columns: 1fr; }
  .ys-scenes-grid { grid-template-columns: repeat(2, 1fr); }
  .ys-gallery-grid { grid-template-columns: repeat(2, 1fr); }
  .ys-stats-grid { grid-template-columns: repeat(2, 1fr); }
  .ys-testimonials-grid { grid-template-columns: 1fr; }
  .ys-footer-grid { grid-template-columns: 1fr 1fr; gap: 32px; }
  .ys-footer-grid .ys-footer-col:first-child { grid-column: 1 / -1; }
  section { padding: 64px 0; }
  .ys-hero { padding: 48px 0 64px; }
  .ys-cta-card { padding: 40px 24px; }
}
@media (max-width: 480px) {
  .ys-scenes-grid { grid-template-columns: 1fr; }
  .ys-gallery-grid { grid-template-columns: 1fr; }
  .ys-stats-grid { grid-template-columns: 1fr; }
  .ys-footer-grid { grid-template-columns: 1fr; }
  .ys-footer-bottom { flex-direction: column; text-align: center; }
}