/* =====================
   小豆AI助手 · 全局变量
   ===================== */
:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --primary-light: #dbeafe;
  --accent: #f59e0b;
  --accent-light: #fef3c7;
  --text: #111827;
  --text-muted: #6b7280;
  --text-light: #9ca3af;
  --bg: #ffffff;
  --bg-subtle: #f8fafc;
  --bg-alt: #f1f5f9;
  --border: #e5e7eb;
  --radius: 12px;
  --radius-lg: 20px;
  --shadow: 0 1px 3px rgba(0,0,0,0.07), 0 4px 16px rgba(0,0,0,0.06);
  --shadow-lg: 0 8px 32px rgba(0,0,0,0.10);
  --font-serif: 'Noto Serif SC', serif;
  --font-sans: 'Noto Sans SC', sans-serif;
}

/* ========= RESET ========= */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  font-family: var(--font-sans);
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
ul { list-style: none; padding: 0; }
img { max-width: 100%; display: block; }

/* ========= UTILITY ========= */
.container {
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 24px;
}
.section { padding: 80px 0; }
.section-label {
  display: inline-block;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--primary);
  background: var(--primary-light);
  padding: 4px 12px;
  border-radius: 100px;
  margin-bottom: 16px;
}
.section-title {
  font-family: var(--font-serif);
  font-size: clamp(24px, 4vw, 36px);
  font-weight: 700;
  color: var(--text);
  margin-bottom: 16px;
  line-height: 1.3;
}
.section-desc {
  font-size: 16px;
  color: var(--text-muted);
  max-width: 720px;
  margin-bottom: 12px;
  line-height: 1.8;
}
.section-desc strong { color: var(--text); }

/* ========= BUTTONS ========= */
.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--primary);
  color: #fff;
  font-weight: 600;
  font-size: 15px;
  padding: 12px 24px;
  border-radius: var(--radius);
  transition: background 0.2s, transform 0.15s, box-shadow 0.2s;
  box-shadow: 0 2px 8px rgba(37,99,235,0.25);
}
.btn-primary:hover {
  background: var(--primary-dark);
  transform: translateY(-1px);
  box-shadow: 0 4px 16px rgba(37,99,235,0.35);
}
.btn-primary.btn-lg { font-size: 17px; padding: 16px 36px; }
.btn-ghost {
  display: inline-flex;
  align-items: center;
  color: var(--text-muted);
  font-size: 15px;
  font-weight: 500;
  padding: 12px 20px;
  border-radius: var(--radius);
  border: 1.5px solid var(--border);
  transition: all 0.2s;
}
.btn-ghost:hover { color: var(--primary); border-color: var(--primary); background: var(--primary-light); }

/* ========= NAVBAR ========= */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255,255,255,0.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  padding: 0 24px;
}
.nav-inner {
  max-width: 1120px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  height: 64px;
  gap: 32px;
}
.logo {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 20px;
  font-weight: 700;
  flex-shrink: 0;
}
.logo-icon { font-size: 24px; }
.logo-text { font-family: var(--font-serif); }
.logo-text em { font-style: normal; color: var(--primary); }
.nav-links {
  display: flex;
  align-items: center;
  gap: 24px;
  flex: 1;
}
.nav-links a {
  font-size: 14px;
  color: var(--text-muted);
  font-weight: 500;
  transition: color 0.2s;
}
.nav-links a:hover { color: var(--primary); }
.btn-nav {
  background: var(--primary);
  color: #fff;
  font-size: 14px;
  font-weight: 600;
  padding: 8px 18px;
  border-radius: 8px;
  flex-shrink: 0;
  transition: background 0.2s;
}
.btn-nav:hover { background: var(--primary-dark); }

/* ========= HERO ========= */
.hero {
  position: relative;
  padding: 100px 24px 80px;
  overflow: hidden;
  text-align: center;
}
.hero-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
  pointer-events: none;
}
.hero-blob {
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
  opacity: 0.25;
}
.b1 {
  width: 600px; height: 600px;
  background: radial-gradient(circle, #3b82f6, #6366f1);
  top: -200px; left: -100px;
}
.b2 {
  width: 500px; height: 500px;
  background: radial-gradient(circle, #f59e0b, #fb923c);
  bottom: -150px; right: -80px;
}
.hero-grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, rgba(37,99,235,0.04) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(37,99,235,0.04) 1px, transparent 1px);
  background-size: 48px 48px;
}
.hero-content {
  position: relative;
  z-index: 1;
  max-width: 820px;
  margin: 0 auto;
}
.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
  font-weight: 600;
  color: #92400e;
  background: var(--accent-light);
  border: 1.5px solid #fcd34d;
  padding: 6px 16px;
  border-radius: 100px;
  margin-bottom: 28px;
  animation: fadeSlideDown 0.6s ease both;
}
.hero-title {
  font-family: var(--font-serif);
  font-size: clamp(36px, 6vw, 60px);
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 24px;
  animation: fadeSlideDown 0.6s 0.1s ease both;
}
.hero-accent {
  color: var(--primary);
  display: block;
  font-size: clamp(22px, 3.5vw, 36px);
  font-weight: 600;
  margin-top: 8px;
}
.hero-desc {
  font-size: 16px;
  color: var(--text-muted);
  line-height: 1.9;
  margin-bottom: 36px;
  animation: fadeSlideDown 0.6s 0.2s ease both;
}
.hero-desc strong { color: var(--text); }
.hero-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 48px;
  animation: fadeSlideDown 0.6s 0.3s ease both;
}
.hero-stats {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0;
  animation: fadeSlideDown 0.6s 0.4s ease both;
}
.stat {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 0 32px;
}
.stat-num {
  font-family: var(--font-serif);
  font-size: 32px;
  font-weight: 700;
  color: var(--primary);
  line-height: 1;
}
.stat-label { font-size: 13px; color: var(--text-muted); margin-top: 4px; }
.stat-divider {
  width: 1px;
  height: 40px;
  background: var(--border);
}

/* ========= INTRO ========= */
.intro { background: var(--bg-subtle); }

/* ========= FEATURES ========= */
.features { background: var(--bg); }
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-top: 48px;
}
.feature-card {
  background: var(--bg-subtle);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 32px;
  transition: box-shadow 0.2s, transform 0.2s;
}
.feature-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-4px);
  border-color: #bfdbfe;
}
.feature-icon { font-size: 36px; margin-bottom: 16px; }
.feature-card h3 {
  font-family: var(--font-serif);
  font-size: 20px;
  font-weight: 700;
  margin-bottom: 12px;
}
.feature-card p { font-size: 14px; color: var(--text-muted); margin-bottom: 16px; line-height: 1.7; }
.feature-card ul li { font-size: 14px; color: var(--text-muted); padding: 3px 0; }

/* ========= HOW TO ========= */
.howto { background: var(--bg-alt); }
.steps {
  display: flex;
  align-items: stretch;
  gap: 0;
  margin-top: 48px;
  flex-wrap: wrap;
  justify-content: center;
}
.step {
  background: var(--bg);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px 24px;
  display: flex;
  flex-direction: column;
  justify-content: flex-start;
  flex: 1;
  min-width: 180px;
  max-width: 220px;
  text-align: center;
}
.step-num {
  font-family: var(--font-serif);
  font-size: 36px;
  font-weight: 700;
  color: var(--primary-light);
  margin-bottom: 12px;
  -webkit-text-stroke: 2px var(--primary);
}
.step h3 { font-size: 16px; font-weight: 700; margin-bottom: 10px; }
.step p { font-size: 13px; color: var(--text-muted); line-height: 1.6; }
.step p a { color: var(--primary); text-decoration: underline; }
.step-arrow {
  display: flex;
  align-items: center;
  font-size: 24px;
  color: var(--text-light);
  padding: 0 8px;
  flex-shrink: 0;
}

/* ========= PLATFORMS ========= */
.platforms { background: var(--bg); }
.platform-cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-top: 48px;
}
.platform-card {
  background: var(--bg-subtle);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 32px;
  position: relative;
  display: flex;
  flex-direction: column;
  transition: box-shadow 0.2s;
}
.platform-card.featured {
  border-color: var(--primary);
  background: linear-gradient(135deg, #eff6ff, #f8fafc);
  box-shadow: 0 0 0 4px rgba(37,99,235,0.08);
}
.platform-badge {
  position: absolute;
  top: -12px;
  left: 24px;
  background: var(--primary);
  color: #fff;
  font-size: 12px;
  font-weight: 700;
  padding: 4px 12px;
  border-radius: 100px;
}
.platform-icon { font-size: 40px; margin-bottom: 16px; }
.platform-card h3 { font-family: var(--font-serif); font-size: 18px; font-weight: 700; margin-bottom: 6px; }
.platform-sub { font-size: 13px; color: var(--text-muted); margin-bottom: 16px; }
.platform-card ul { margin-bottom: 20px; }
.platform-card ul li { font-size: 14px; color: var(--text-muted); padding: 4px 0; }
.platform-desc {
  min-height: 44px;
  font-size: 14px;
  color: var(--text-muted);
  line-height: 1.7;
  margin-bottom: 16px;
}
.platform-note { font-size: 12px; color: var(--text-light); margin-top: 12px; }
.qrcode-placeholder {
  margin: 16px 0 0;
  min-height: 196px;
  display: flex;
  align-items: center;
  justify-content: center;
}
.qrcode-image {
  display: block;
  width: 100%;
  max-width: 180px;
  margin: 0 auto;
  border-radius: 16px;
  background: #fff;
  box-shadow: 0 10px 24px rgba(15, 23, 42, 0.08);
}
.qrcode-card .platform-note { margin-top: auto; }

/* ========= SCENARIOS ========= */
.scenarios { background: var(--bg-subtle); }
.scenario-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
  margin-top: 48px;
}
.scenario-card {
  background: var(--bg);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px;
  transition: box-shadow 0.2s, transform 0.2s;
}
.scenario-card:hover { box-shadow: var(--shadow-lg); transform: translateY(-3px); }
.scenario-icon { font-size: 32px; margin-bottom: 12px; }
.scenario-card h3 { font-family: var(--font-serif); font-size: 18px; font-weight: 700; margin-bottom: 12px; }
.scenario-card p { font-size: 14px; color: var(--text-muted); margin-bottom: 14px; line-height: 1.7; }
.scenario-card ul li { font-size: 13px; color: var(--text-muted); padding: 3px 0; }

/* ========= TUTORIALS ========= */
.tutorials { background: var(--bg); }
.tutorial-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  margin-top: 48px;
}
.tutorial-card {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  background: var(--bg-subtle);
  border: 1.5px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 20px;
  transition: all 0.2s;
  cursor: pointer;
}
.tutorial-card:hover {
  border-color: var(--primary);
  background: var(--primary-light);
  transform: translateY(-2px);
}
.tut-icon { font-size: 24px; flex-shrink: 0; }
.tutorial-card h4 { font-size: 14px; font-weight: 700; margin-bottom: 4px; }
.tutorial-card p { font-size: 12px; color: var(--text-muted); }
.tutorial-more { text-align: center; margin-top: 32px; }

/* ========= FAQ ========= */
.faq { background: var(--bg-subtle); }
.faq-list {
  max-width: 760px;
  margin: 48px auto 0;
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.faq-item {
  background: var(--bg);
  border: 1.5px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: border-color 0.2s;
}
.faq-item[open] { border-color: var(--primary); }
.faq-item summary {
  font-size: 16px;
  font-weight: 600;
  padding: 20px 24px;
  cursor: pointer;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  user-select: none;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: '+';
  font-size: 20px;
  color: var(--primary);
  transition: transform 0.2s;
  flex-shrink: 0;
}
.faq-item[open] summary::after { transform: rotate(45deg); }
.faq-item p {
  padding: 0 24px 20px;
  font-size: 14px;
  color: var(--text-muted);
  line-height: 1.8;
  border-top: 1px solid var(--border);
  padding-top: 16px;
}

/* ========= CTA ========= */
.cta { background: linear-gradient(135deg, #1e40af 0%, #2563eb 60%, #3b82f6 100%); }
.cta-inner {
  text-align: center;
  padding: 16px 0;
}
.cta-inner h2 {
  font-family: var(--font-serif);
  font-size: clamp(24px, 4vw, 36px);
  font-weight: 700;
  color: #fff;
  margin-bottom: 12px;
}
.cta-inner p { color: rgba(255,255,255,0.75); font-size: 16px; margin-bottom: 32px; }
.cta-inner .btn-primary {
  background: #fff;
  color: var(--primary);
  box-shadow: 0 4px 24px rgba(0,0,0,0.15);
}
.cta-inner .btn-primary:hover { background: var(--primary-light); }

/* ========= FOOTER ========= */
.footer {
  background: #0f172a;
  color: #94a3b8;
  padding: 64px 0 0;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  padding-bottom: 40px;
  border-bottom: 1px solid #1e293b;
}
.footer-brand .logo { color: #fff; margin-bottom: 16px; }
.footer-brand p { font-size: 14px; line-height: 1.7; margin-bottom: 16px; }
.footer-meta { display: flex; flex-direction: column; gap: 4px; font-size: 13px; }
.footer-meta strong { color: #e2e8f0; }
.footer-links h4 { color: #e2e8f0; font-size: 14px; font-weight: 700; margin-bottom: 16px; }
.footer-links a, .footer-links span {
  display: block;
  font-size: 13px;
  color: #64748b;
  padding: 4px 0;
  transition: color 0.2s;
}
.footer-links a:hover { color: #93c5fd; }
.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 20px 0;
  font-size: 12px;
  color: #475569;
  flex-wrap: wrap;
  gap: 8px;
}

/* ========= FLOAT ========= */
.float-menu {
  position: fixed;
  bottom: 24px;
  right: 24px;
  z-index: 200;
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 8px;
}
.float-toggle {
  background: var(--primary);
  color: #fff;
  font-size: 14px;
  font-weight: 700;
  padding: 12px 20px;
  border-radius: 100px;
  border: none;
  cursor: pointer;
  box-shadow: 0 4px 24px rgba(37,99,235,0.4);
  transition: background 0.2s, transform 0.15s;
}
.float-toggle:hover { background: var(--primary-dark); transform: scale(1.05); }
.float-links {
  display: none;
  flex-direction: column;
  gap: 8px;
  align-items: flex-end;
}
.float-links.open { display: flex; }
.float-links a {
  background: #fff;
  color: var(--text);
  font-size: 13px;
  font-weight: 600;
  padding: 10px 18px;
  border-radius: 100px;
  box-shadow: var(--shadow-lg);
  transition: all 0.2s;
}
.float-links a:hover { background: var(--primary-light); color: var(--primary); }

/* ========= ANIMATIONS ========= */
@keyframes fadeSlideDown {
  from { opacity: 0; transform: translateY(-16px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ========= RESPONSIVE ========= */
@media (max-width: 900px) {
  .features-grid { grid-template-columns: 1fr; }
  .platform-cards { grid-template-columns: 1fr; }
  .scenario-grid { grid-template-columns: 1fr; }
  .tutorial-grid { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .steps { gap: 12px; }
  .step-arrow { display: none; }
}
@media (max-width: 640px) {
  .nav-links { display: none; }
  .hero { padding: 60px 16px 48px; }
  .hero-stats { flex-wrap: wrap; gap: 16px; }
  .stat-divider { display: none; }
  .tutorial-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; }
  .footer-bottom { flex-direction: column; align-items: flex-start; }
}