/* ============================================================
   老冯AI工作站 — 白酒行业人的AI学习交流平台
   设计关键词: 稳重 · 可信 · 接地气 · 行业感 · 暖光 · 酒馆
   目标用户: 30-50岁白酒行业从业者
   ============================================================ */

/* ---------- CSS Variables / Design Tokens ---------- */
:root {
  /* Brand Colors */
  --color-bg-deep:     #15110D;
  --color-bg-wood:     #241A13;
  --color-bg-card:     #1E1812;
  --color-bg-surface:  #2A1F16;
  --color-bg-warm:     #F5F1EA;
  --color-bg-cream:    #EDE7DE;
  --color-bg-light:    #FAF8F5;

  /* Accent */
  --color-gold:        #C08A4A;
  --color-gold-light:  #D4A85E;
  --color-gold-dark:   #A07238;
  --color-gold-subtle: rgba(192, 138, 74, 0.12);

  /* Text */
  --color-text-primary:   #F5F1EA;
  --color-text-secondary: #B8AA98;
  --color-text-muted:     #8A7D6E;
  --color-text-dark:      #2A1F16;
  --color-text-body:      #3D3226;

  /* Borders & Dividers */
  --color-border:       #3A2F22;
  --color-border-light: #D9CFC0;
  --color-divider:      rgba(192, 138, 74, 0.15);

  /* Typography — 面向30-50岁读者，正文不小于16px，辅助文字不小于14px */
  --font-sans: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", system-ui, -apple-system, sans-serif;
  --font-mono: "SF Mono", "Fira Code", "Consolas", monospace;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;
  --space-4xl: 6rem;

  /* Container */
  --container-max: 1100px;
  --container-padding: 1.25rem;

  /* Radii */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;

  /* Shadows */
  --shadow-card: 0 1px 3px rgba(0,0,0,0.08);
  --shadow-card-hover: 0 4px 16px rgba(0,0,0,0.1);
  --shadow-gold: 0 0 40px rgba(192, 138, 74, 0.06);

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-base: 0.25s ease;
  --transition-slow: 0.4s ease;
}

/* ---------- Reset & Base ---------- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: 1rem;
  color: var(--color-text-dark);
  background: var(--color-bg-light);
  line-height: 1.8;
  letter-spacing: 0.01em;
  overflow-x: hidden;
}

img {
  max-width: 100%;
  display: block;
}

a {
  color: var(--color-gold-dark);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-gold);
}

/* ---------- Container ---------- */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-padding);
}

/* ---------- Typography ---------- */
.section-label {
  display: inline-block;
  font-size: 0.875rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--color-gold);
  margin-bottom: var(--space-sm);
}

.section-title {
  font-size: clamp(1.65rem, 3.5vw, 2.2rem);
  font-weight: 700;
  color: var(--color-text-dark);
  margin-bottom: var(--space-md);
  line-height: 1.35;
}

.section-desc {
  font-size: 1.05rem;
  color: var(--color-text-muted);
  max-width: 640px;
  margin-bottom: var(--space-2xl);
  line-height: 1.85;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.75rem 1.75rem;
  font-size: 1rem;
  font-weight: 600;
  font-family: var(--font-sans);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-base);
  border: none;
  text-decoration: none;
  line-height: 1.4;
  min-height: 44px;
}

.btn-primary {
  background: var(--color-gold);
  color: #fff;
}

.btn-primary:hover {
  background: var(--color-gold-light);
  color: #fff;
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(192, 138, 74, 0.3);
}

.btn-outline {
  background: transparent;
  color: var(--color-gold);
  border: 1.5px solid var(--color-gold);
}

.btn-outline:hover {
  background: var(--color-gold-subtle);
  color: var(--color-gold-light);
}

.btn-ghost {
  background: transparent;
  color: var(--color-text-secondary);
  padding: 0.5rem 1rem;
}

.btn-ghost:hover {
  color: var(--color-gold);
}

/* ---------- Navigation ---------- */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(21, 17, 13, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(192, 138, 74, 0.08);
  transition: all var(--transition-base);
}

.nav.scrolled {
  background: rgba(21, 17, 13, 0.97);
  border-bottom-color: rgba(192, 138, 74, 0.15);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-padding);
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--color-text-primary);
  text-decoration: none;
  letter-spacing: 0.02em;
}

.nav-brand-icon {
  width: 30px;
  height: 30px;
  background: var(--color-gold);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.95rem;
  color: #fff;
  flex-shrink: 0;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  list-style: none;
}

.nav-links a {
  display: flex;
  align-items: center;
  padding: 0.5rem 0.85rem;
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  text-decoration: none;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  white-space: nowrap;
  min-height: 40px;
}

.nav-links a:hover {
  color: var(--color-text-primary);
  background: rgba(192, 138, 74, 0.08);
}

/* Mobile menu button */
.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  z-index: 101;
  min-width: 44px;
  min-height: 44px;
  align-items: center;
  justify-content: center;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--color-text-secondary);
  border-radius: 1px;
  transition: all var(--transition-base);
}

.nav-toggle.active span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.nav-toggle.active span:nth-child(2) {
  opacity: 0;
}

.nav-toggle.active span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* ---------- Hero Section ---------- */
.hero {
  background: var(--color-bg-deep);
  background-image: url(../assets/hero-bg.png);
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  min-height: 100vh;
  display: flex;
  align-items: center;
  position: relative;
  overflow: hidden;
}

/* 深色遮罩 — 保证背景图上的文字可读 */
.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: rgba(21, 17, 13, 0.62);
  z-index: 0;
  pointer-events: none;
}

/* 细微纹理 — 叠加在遮罩之上 */
.hero::after {
  content: '';
  position: absolute;
  inset: 0;
  z-index: 0;
  background:
    repeating-linear-gradient(
      0deg,
      transparent,
      transparent 2px,
      rgba(192, 138, 74, 0.02) 2px,
      rgba(192, 138, 74, 0.02) 4px
    );
  pointer-events: none;
}

.hero-content {
  position: relative;
  z-index: 1;
  padding: 120px 0 80px;
  max-width: 720px;
}

.hero h1 {
  font-size: clamp(2.4rem, 5.5vw, 3.4rem);
  font-weight: 800;
  color: var(--color-text-primary);
  line-height: 1.15;
  margin-bottom: var(--space-md);
  letter-spacing: 0.01em;
}

.hero h1 span {
  color: var(--color-gold);
}

.hero-subtitle {
  font-size: clamp(1.05rem, 2vw, 1.25rem);
  color: var(--color-gold-light);
  font-weight: 500;
  margin-bottom: var(--space-lg);
  letter-spacing: 0.03em;
}

.hero-desc {
  font-size: 1.05rem;
  color: var(--color-text-secondary);
  line-height: 1.95;
  margin-bottom: var(--space-2xl);
  max-width: 600px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-md);
}

/* ---------- Section Base ---------- */
.section {
  padding: var(--space-4xl) 0;
}

.section-alt {
  background: var(--color-bg-warm);
}

.section-dark {
  background: var(--color-bg-deep);
  color: var(--color-text-primary);
}

.section-dark .section-title {
  color: var(--color-text-primary);
}

.section-dark .section-desc {
  color: var(--color-text-secondary);
}

.section-header {
  text-align: center;
  margin-bottom: var(--space-3xl);
}

.section-header .section-desc {
  margin-left: auto;
  margin-right: auto;
}

/* ---------- Cards Grid ---------- */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--space-lg);
}

.card {
  background: #fff;
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  transition: all var(--transition-base);
}

.card:hover {
  border-color: var(--color-gold);
  box-shadow: var(--shadow-card-hover);
  transform: translateY(-2px);
}

.card-icon {
  width: 48px;
  height: 48px;
  background: var(--color-gold-subtle);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  margin-bottom: var(--space-md);
  color: var(--color-gold);
}

.card h3 {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-text-dark);
  margin-bottom: var(--space-sm);
}

.card p {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  line-height: 1.75;
}

/* Dark background cards */
.section-dark .card {
  background: var(--color-bg-card);
  border-color: var(--color-border);
}

.section-dark .card h3 {
  color: var(--color-text-primary);
}

.section-dark .card p {
  color: var(--color-text-secondary);
}

.section-dark .card:hover {
  border-color: var(--color-gold);
  background: var(--color-bg-surface);
}

/* ---------- About Section ---------- */
.about-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-3xl);
  align-items: start;
}

.about-text {
  font-size: 1.05rem;
  line-height: 1.95;
  color: var(--color-text-body);
}

.about-text p {
  margin-bottom: var(--space-lg);
}

.about-highlights {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.about-highlight {
  display: flex;
  align-items: flex-start;
  gap: var(--space-md);
  padding: var(--space-lg);
  background: #fff;
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-md);
  border-left: 3px solid var(--color-gold);
}

.about-highlight-icon {
  font-size: 1.3rem;
  flex-shrink: 0;
  margin-top: 2px;
}

.about-highlight h4 {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--color-text-dark);
  margin-bottom: 2px;
}

.about-highlight p {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin: 0;
  line-height: 1.65;
}

/* ---------- Why Section ---------- */
.why-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: var(--space-lg);
  margin-top: var(--space-xl);
}

.why-item {
  display: flex;
  gap: var(--space-md);
  padding: var(--space-lg);
}

.why-item-num {
  width: 40px;
  height: 40px;
  background: var(--color-gold);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.95rem;
  flex-shrink: 0;
}

.why-item h4 {
  font-size: 1.05rem;
  font-weight: 700;
  margin-bottom: 4px;
  color: var(--color-text-dark);
}

.why-item p {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  line-height: 1.7;
  margin: 0;
}

/* ---------- Content Cards (Free / Paid) ---------- */
.content-card {
  background: #fff;
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.content-card:hover {
  border-color: var(--color-gold);
  box-shadow: var(--shadow-card-hover);
}

.content-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--color-gold);
  opacity: 0;
  transition: opacity var(--transition-base);
}

.content-card:hover::before {
  opacity: 1;
}

.content-card .card-icon {
  width: 48px;
  height: 48px;
  font-size: 1.4rem;
}

.content-card h3 {
  font-size: 1.1rem;
  margin-bottom: var(--space-sm);
}

.content-card ul {
  list-style: none;
  padding: 0;
}

.content-card ul li {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  padding: 0.3rem 0;
  padding-left: 1.3rem;
  position: relative;
  line-height: 1.55;
}

.content-card ul li::before {
  content: '·';
  position: absolute;
  left: 0.3rem;
  color: var(--color-gold);
  font-weight: 700;
}

/* Dark section content cards */
.section-dark .content-card {
  background: var(--color-bg-card);
  border-color: var(--color-border);
}

.section-dark .content-card h3 {
  color: var(--color-text-primary);
}

.section-dark .content-card p {
  color: var(--color-text-secondary);
}

.section-dark .content-card ul li {
  color: var(--color-text-secondary);
}

.section-dark .content-card:hover {
  border-color: var(--color-gold);
  background: var(--color-bg-surface);
}

.section-dark .content-card .card-icon {
  background: rgba(192, 138, 74, 0.12);
}

/* ── 免费/付费标签 — 一眼可辨 ── */
.badge-free {
  display: inline-block;
  background: #E8F5E9;
  color: #2E7D32;
  font-size: 0.8rem;
  font-weight: 700;
  padding: 0.25rem 0.75rem;
  border-radius: 100px;
  margin-bottom: var(--space-md);
  letter-spacing: 0.03em;
  border: 1px solid #C8E6C9;
}

/* 免费卡片在深色背景时微调 */
.section-dark .badge-free {
  background: rgba(46, 125, 50, 0.2);
  color: #66BB6A;
  border-color: rgba(46, 125, 50, 0.25);
}

.badge-paid {
  display: inline-block;
  background: var(--color-gold-subtle);
  color: var(--color-gold-dark);
  font-size: 0.8rem;
  font-weight: 700;
  padding: 0.25rem 0.75rem;
  border-radius: 100px;
  margin-bottom: var(--space-md);
  letter-spacing: 0.03em;
  border: 1px solid rgba(192, 138, 74, 0.25);
}

/* ---------- Observation Section ---------- */
.obs-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--space-md);
}

.obs-item {
  display: flex;
  align-items: flex-start;
  gap: var(--space-md);
  padding: var(--space-lg);
  background: #fff;
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-md);
  transition: all var(--transition-base);
}

.obs-item:hover {
  border-color: var(--color-gold);
  background: #FFFDF9;
}

.obs-item-icon {
  font-size: 1.3rem;
  flex-shrink: 0;
  margin-top: 2px;
}

.obs-item h4 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-text-dark);
  margin-bottom: 3px;
}

.obs-item p {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  margin: 0;
  line-height: 1.65;
}

/* ---------- Agent Placeholder Cards ---------- */
.agent-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-lg);
}

.agent-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  text-align: center;
  transition: all var(--transition-base);
}

.agent-card:hover {
  border-color: var(--color-gold);
  transform: translateY(-2px);
}

.agent-card-icon {
  width: 56px;
  height: 56px;
  background: var(--color-gold-subtle);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin: 0 auto var(--space-md);
}

.agent-card h4 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-text-primary);
  margin-bottom: var(--space-xs);
}

.agent-card .coming-soon {
  font-size: 0.8rem;
  color: var(--color-gold-light);
  letter-spacing: 0.04em;
  font-weight: 500;
}

.agent-card .agent-desc {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin-top: 4px;
  line-height: 1.55;
}

/* Agent 卡片作为链接 */
.agent-link {
  text-decoration: none;
  color: inherit;
  cursor: pointer;
}

.agent-link:hover {
  border-color: var(--color-gold);
  transform: translateY(-2px);
  box-shadow: 0 4px 20px rgba(0,0,0,0.3);
}

.agent-link:hover .agent-btn {
  background: var(--color-gold);
  color: #fff;
}

/* Agent 副标题 */
.agent-subtitle {
  font-size: 0.85rem;
  color: var(--color-gold-light);
  margin-bottom: var(--space-sm);
  font-weight: 500;
}

/* Agent 按钮 */
.agent-btn {
  display: inline-block;
  margin-top: var(--space-md);
  padding: 0.45rem 1.1rem;
  font-size: 0.85rem;
  font-weight: 600;
  font-family: var(--font-sans);
  border-radius: var(--radius-sm);
  background: rgba(192, 138, 74, 0.15);
  color: var(--color-gold-light);
  transition: all var(--transition-fast);
  border: 1px solid rgba(192, 138, 74, 0.2);
}

.agent-btn-ghost {
  background: transparent;
  color: var(--color-text-muted);
  border: 1px dashed var(--color-border);
}

/* 增强 agent-grid 在桌面端的列数 */
@media (min-width: 1025px) {
  .agent-grid {
    grid-template-columns: repeat(5, 1fr);
  }
}

/* Observation placeholder card */
.obs-item.obs-placeholder {
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-bg-cream);
  border-style: dashed;
  min-height: 88px;
}

.obs-placeholder p {
  color: var(--color-text-muted);
  font-size: 0.9rem;
  margin: 0;
}

/* ---------- Platform Cards (微信生态入口) ---------- */
.platform-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(175px, 1fr));
  gap: var(--space-lg);
}

.platform-card {
  background: #fff;
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  text-align: center;
  transition: all var(--transition-base);
  cursor: default;
}

.platform-card:hover {
  border-color: var(--color-gold);
  box-shadow: var(--shadow-card-hover);
  transform: translateY(-2px);
}

.platform-icon {
  width: 64px;
  height: 64px;
  background: var(--color-bg-cream);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.8rem;
  margin: 0 auto var(--space-md);
}

.platform-card h4 {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--color-text-dark);
  margin-bottom: 4px;
}

.platform-card p {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  margin: 0;
}

/* QR Code placeholder — 明确是占位，方便后续替换 */
.qr-placeholder {
  width: 110px;
  height: 110px;
  background: var(--color-bg-cream);
  border: 2px dashed #C8BDA8;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: var(--space-lg) auto 0;
  font-size: 0.8rem;
  color: #B0A08A;
  text-align: center;
  line-height: 1.5;
  padding: 0.5rem;
  transition: border-color var(--transition-base);
}

.platform-card:hover .qr-placeholder {
  border-color: var(--color-gold);
}

/* QR 真实图片 — 替换占位后使用 */
.qr-image {
  width: 110px;
  height: 110px;
  object-fit: contain;
  margin: var(--space-lg) auto 0;
  display: block;
  border-radius: var(--radius-sm);
}

/* ---------- Contact Section ---------- */
.contact-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-3xl);
  align-items: center;
}

.contact-text {
  font-size: 1.05rem;
  line-height: 1.95;
  color: var(--color-text-body);
}

.contact-links {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.contact-link {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: var(--space-lg);
  background: #fff;
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-md);
  text-decoration: none;
  transition: all var(--transition-base);
  min-height: 64px;
}

.contact-link:hover {
  border-color: var(--color-gold);
  background: #FFFDF9;
}

.contact-link-icon {
  font-size: 1.4rem;
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-bg-cream);
  border-radius: var(--radius-sm);
}

.contact-link h4 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-text-dark);
  margin-bottom: 2px;
}

.contact-link p {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin: 0;
}

/* ---------- Footer ---------- */
.footer {
  background: var(--color-bg-deep);
  padding: var(--space-3xl) 0 var(--space-xl);
  color: var(--color-text-secondary);
  font-size: 0.875rem;
  text-align: center;
}

.footer-brand {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-text-primary);
  margin-bottom: var(--space-sm);
}

.footer-desc {
  color: var(--color-text-muted);
  max-width: 420px;
  margin: 0 auto var(--space-xl);
  line-height: 1.75;
  font-size: 0.9rem;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: var(--space-xl);
  flex-wrap: wrap;
  margin-bottom: var(--space-xl);
}

.footer-links a {
  color: var(--color-text-muted);
  font-size: 0.875rem;
}

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

.footer-bottom {
  border-top: 1px solid var(--color-border);
  padding-top: var(--space-lg);
  color: var(--color-text-muted);
  font-size: 0.8rem;
  line-height: 1.7;
}

/* ---------- Section Divider ---------- */
.section-divider {
  width: 60px;
  height: 3px;
  background: var(--color-gold);
  margin: 0 auto var(--space-2xl);
  border-radius: 2px;
}

/* ============================================================
   响应式断点
   375px  iPhone SE / 小屏安卓
   414px  iPhone 11 / 主流手机
   768px  平板竖屏 / 大折叠
   1024px 平板横屏 / 小笔记本
   1440px 桌面大屏
   ============================================================ */

/* ── ≤1440px: 大屏微调 ── */
@media (max-width: 1440px) {
  .hero-content {
    max-width: 680px;
  }
}

/* ── ≤1024px: 平板/小笔记本 ── */
@media (max-width: 1024px) {
  :root {
    --space-4xl: 5rem;
    --space-3xl: 3.5rem;
    --space-2xl: 2.5rem;
  }

  .about-content {
    gap: var(--space-2xl);
  }

  .contact-content {
    gap: var(--space-2xl);
  }

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

  .obs-list {
    grid-template-columns: repeat(2, 1fr);
  }

  .platform-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

/* ── ≤768px: 平板竖屏 / 手机横屏 ── */
@media (max-width: 768px) {
  :root {
    --space-4xl: 3.5rem;
    --space-3xl: 2.5rem;
    --space-2xl: 2rem;
    --container-padding: 1rem;
  }

  /* Mobile nav */
  .nav-links {
    position: fixed;
    top: 0;
    right: -100%;
    width: 280px;
    height: 100vh;
    height: 100dvh;
    background: var(--color-bg-deep);
    flex-direction: column;
    padding: 80px var(--space-xl) var(--space-xl);
    gap: 0;
    transition: right var(--transition-slow);
    border-left: 1px solid var(--color-border);
    overflow-y: auto;
  }

  .nav-links.active {
    right: 0;
  }

  .nav-links a {
    padding: 0.85rem 0;
    font-size: 1.05rem;
    border-bottom: 1px solid var(--color-border);
    width: 100%;
    border-radius: 0;
    min-height: 48px;
  }

  .nav-toggle {
    display: flex;
  }

  /* Hero */
  .hero-content {
    padding: 100px 0 60px;
  }

  .hero h1 {
    font-size: clamp(2rem, 7vw, 2.6rem);
  }

  .hero-desc {
    font-size: 1rem;
  }

  .hero-actions {
    flex-direction: column;
    align-items: flex-start;
  }

  .hero-actions .btn {
    width: 100%;
    justify-content: center;
  }

  /* Stack layouts */
  .about-content,
  .contact-content {
    grid-template-columns: 1fr;
    gap: var(--space-2xl);
  }

  .cards-grid {
    grid-template-columns: 1fr;
    gap: var(--space-md);
  }

  .why-list {
    grid-template-columns: 1fr;
  }

  .obs-list {
    grid-template-columns: 1fr;
  }

  .agent-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-md);
  }

  .platform-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-md);
  }

  /* Section titles */
  .section-title {
    font-size: 1.5rem;
  }

  .section-desc {
    font-size: 1rem;
  }

  /* Content cards */
  .content-card {
    padding: var(--space-lg);
  }

  .content-card ul li {
    font-size: 0.875rem;
  }
}

/* ── ≤414px: iPhone 11 / 主流手机 ── */
@media (max-width: 414px) {
  :root {
    --space-4xl: 3rem;
    --space-3xl: 2rem;
    --space-2xl: 1.75rem;
    --space-xl: 1.5rem;
  }

  .hero {
    min-height: auto;
    padding: 0;
  }

  .hero-content {
    padding: 90px 0 50px;
  }

  .hero h1 {
    font-size: 1.9rem;
  }

  .hero-subtitle {
    font-size: 1rem;
  }

  .hero-desc {
    font-size: 0.95rem;
    line-height: 1.8;
  }

  .section-title {
    font-size: 1.4rem;
  }

  .section-desc {
    font-size: 0.95rem;
  }

  .about-text {
    font-size: 1rem;
  }

  .card {
    padding: var(--space-lg);
  }

  .card h3 {
    font-size: 1.05rem;
  }

  .card p {
    font-size: 0.9rem;
  }

  .agent-grid {
    grid-template-columns: 1fr 1fr;
  }

  .agent-card {
    padding: var(--space-lg);
  }

  .agent-card-icon {
    width: 48px;
    height: 48px;
    font-size: 1.3rem;
  }

  .platform-grid {
    grid-template-columns: 1fr 1fr;
  }

  .platform-card {
    padding: var(--space-lg);
  }

  .platform-icon {
    width: 52px;
    height: 52px;
    font-size: 1.5rem;
  }

  .qr-placeholder {
    width: 90px;
    height: 90px;
    font-size: 0.72rem;
  }

  .contact-link {
    padding: var(--space-md) var(--space-lg);
  }

  .footer-links {
    gap: var(--space-md);
  }
}

/* ── ≤375px: iPhone SE / 小屏安卓 ── */
@media (max-width: 375px) {
  :root {
    --space-4xl: 2.5rem;
    --space-3xl: 1.75rem;
    --space-2xl: 1.5rem;
    --space-xl: 1.25rem;
    --space-lg: 1.25rem;
    --space-md: 0.875rem;
  }

  .hero-content {
    padding: 80px 0 40px;
  }

  .hero h1 {
    font-size: 1.7rem;
  }

  .hero-subtitle {
    font-size: 0.95rem;
  }

  .hero-desc {
    font-size: 0.9rem;
    line-height: 1.75;
  }

  .hero-actions .btn {
    font-size: 0.95rem;
    padding: 0.7rem 1.25rem;
  }

  .section-title {
    font-size: 1.3rem;
  }

  .section-desc {
    font-size: 0.9rem;
  }

  .nav-brand {
    font-size: 0.95rem;
  }

  .agent-grid,
  .platform-grid {
    grid-template-columns: 1fr;
    gap: var(--space-md);
  }

  .card,
  .content-card {
    padding: var(--space-md);
  }

  .obs-item {
    padding: var(--space-md);
  }

  .qr-placeholder {
    width: 80px;
    height: 80px;
    font-size: 0.68rem;
  }

  .footer {
    padding: var(--space-2xl) 0 var(--space-md);
  }

  .footer-links {
    gap: var(--space-sm);
  }

  .footer-links a {
    font-size: 0.8rem;
  }
}

/* ── ≥1440px: 大桌面优化 ── */
@media (min-width: 1440px) {
  :root {
    --container-max: 1200px;
  }

  .hero-content {
    max-width: 760px;
  }

  .cards-grid {
    gap: var(--space-xl);
  }

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

/* ---------- Overlay for mobile nav ---------- */
.nav-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  z-index: 99;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-base);
}

.nav-overlay.active {
  opacity: 1;
  pointer-events: auto;
}

/* ---------- 背景音乐按钮 ---------- */
.music-toggle {
  position: fixed;
  bottom: 20px;
  right: 20px;
  z-index: 200;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--color-gold);
  color: #fff;
  border: none;
  font-size: 1.3rem;
  cursor: pointer;
  box-shadow: 0 2px 12px rgba(0,0,0,0.3);
  transition: all 0.3s ease;
  display: flex;
  align-items: center;
  justify-content: center;
}
.music-toggle:hover {
  background: var(--color-gold-light);
  transform: scale(1.08);
}
.music-toggle.playing {
  animation: pulse 2s infinite;
}
.music-toggle.paused {
  opacity: 0.6;
  background: #888;
}
@keyframes pulse {
  0%, 100% { box-shadow: 0 2px 12px rgba(0,0,0,0.3); }
  50% { box-shadow: 0 2px 24px rgba(192,138,74,0.6); }
}

/* ---------- Utilities ---------- */
.text-center { text-align: center; }
.mt-0 { margin-top: 0; }
.mb-0 { margin-bottom: 0; }
.mb-sm { margin-bottom: var(--space-sm); }
.mb-md { margin-bottom: var(--space-md); }
.mb-lg { margin-bottom: var(--space-lg); }
.mb-xl { margin-bottom: var(--space-xl); }