/* ================================================================
   求职星 AI面试助手 — Design System
   Version: 1.0.0
   ================================================================ */

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

:root {
  /* Primary palette */
  --primary: #4F46E5;
  --primary-dark: #4338CA;
  --primary-light: #818CF8;
  --accent: #F59E0B;
  --accent-soft: #FEF3C7;
  
  /* Backgrounds & surfaces */
  --bg: #FFFFFF;
  --bg-soft: #F8FAFC;
  --bg-card: #FFFFFF;
  
  /* Text colors */
  --ink: #0F172A;
  --muted: #64748B;
  
  /* Borders */
  --border: #E2E8F0;
  
  /* Semantic */
  --success: #22C55E;
  --info: #3B82F6;
  --warning: #F59E0B;
  --error: #EF4444;
  
  /* Gradients */
  --gradient-primary: linear-gradient(135deg, #4F46E5 0%, #7C3AED 100%);
  --gradient-accent: linear-gradient(135deg, #F59E0B 0%, #F97316 100%);
  --gradient-hero: linear-gradient(180deg, #F8FAFC 0%, #EEF2FF 50%, #F8FAFC 100%);
  --gradient-footer: linear-gradient(180deg, #0F172A 0%, #1E293B 100%);
  --gradient-cta: linear-gradient(135deg, #4F46E5 0%, #7C3AED 50%, #A855F7 100%);
  
  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.05);
  --shadow-md: 0 4px 12px rgba(15, 23, 42, 0.08);
  --shadow-lg: 0 12px 32px rgba(15, 23, 42, 0.12);
  --shadow-xl: 0 20px 48px rgba(15, 23, 42, 0.16);
  --shadow-glow: 0 0 40px rgba(79, 70, 229, 0.2);
  
  /* Spacing */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-8: 32px;
  --space-10: 40px;
  --space-12: 48px;
  --space-16: 64px;
  --space-20: 80px;
  --space-24: 96px;
  
  /* Typography */
  --font-family: -apple-system, BlinkMacSystemFont, 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', 'Segoe UI', sans-serif;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.8125rem;
  --font-size-base: 0.9375rem;
  --font-size-md: 1rem;
  --font-size-lg: 1.0625rem;
  --font-size-xl: 1.125rem;
  --font-size-2xl: 1.25rem;
  --font-size-3xl: 1.5rem;
  --font-size-4xl: 2rem;
  
  /* Border radius */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 20px;
  --radius-2xl: 24px;
  --radius-full: 9999px;
  
  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 350ms ease;
  
  /* Z-index scale */
  --z-dropdown: 100;
  --z-navbar: 1000;
  --z-modal: 2000;
  --z-skip: 3000;
}

/* === Base Styles === */
html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: 1.7;
  color: var(--ink);
  background-color: var(--bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

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

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

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

ul, ol {
  list-style: none;
}

/* === Layout === */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: var(--space-24) 0;
}

.section-head {
  max-width: 720px;
  margin: 0 auto var(--space-16);
  text-align: center;
}

.section-eyebrow {
  display: inline-block;
  font-size: var(--font-size-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--primary);
  background: var(--accent-soft);
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-full);
  margin-bottom: var(--space-4);
}

.section-title {
  font-size: clamp(28px, 4vw, 42px);
  font-weight: 700;
  line-height: 1.2;
  color: var(--ink);
  margin-bottom: var(--space-4);
}

.section-subtitle {
  font-size: var(--font-size-lg);
  color: var(--muted);
  line-height: 1.8;
}

/* === Navbar === */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  width: 100%;
  z-index: var(--z-navbar);
  transition: var(--transition-base);
  background: transparent;
}

.navbar.scrolled {
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  box-shadow: var(--shadow-md);
}

.navbar-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 68px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--ink);
  text-decoration: none;
  transition: var(--transition-fast);
}

.logo:hover {
  color: var(--primary);
}

.logo-icon svg {
  width: 36px;
  height: 36px;
}

.nav-links {
  display: none;
  align-items: center;
  gap: 28px;
}

@media (min-width: 768px) {
  .nav-links {
    display: flex;
  }
}

.nav-link {
  font-size: var(--font-size-md);
  color: var(--muted);
  transition: var(--transition-fast);
  position: relative;
}

.nav-link:hover {
  color: var(--primary);
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--primary);
  transition: var(--transition-fast);
}

.nav-link:hover::after {
  width: 100%;
}

.nav-cta {
  display: none;
  gap: 12px;
  align-items: center;
}

@media (min-width: 768px) {
  .nav-cta {
    display: flex;
  }
}

/* Hamburger */
.hamburger {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 40px;
  height: 40px;
  gap: 6px;
  border-radius: var(--radius-sm);
  transition: var(--transition-fast);
}

@media (min-width: 768px) {
  .hamburger {
    display: none;
  }
}

.hamburger span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--ink);
  border-radius: 2px;
  transition: var(--transition-base);
  transform-origin: center;
}

.hamburger.open span:nth-child(1) {
  transform: translateY(8px) rotate(45deg);
}

.hamburger.open span:nth-child(2) {
  opacity: 0;
  transform: scaleX(0);
}

.hamburger.open span:nth-child(3) {
  transform: translateY(-8px) rotate(-45deg);
}

/* Mobile Menu */
.mobile-menu {
  position: fixed;
  top: 68px;
  left: 0;
  right: 0;
  background: var(--bg);
  padding: var(--space-6) 24px;
  border-top: 1px solid var(--border);
  box-shadow: var(--shadow-lg);
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
  transform: translateY(-100%);
  opacity: 0;
  visibility: hidden;
  transition: var(--transition-base);
  z-index: calc(var(--z-navbar) - 1);
}

.mobile-menu.open {
  transform: translateY(0);
  opacity: 1;
  visibility: visible;
}

.mobile-menu .nav-link {
  display: block;
  padding: var(--space-3) 0;
  font-size: var(--font-size-lg);
}

.mobile-menu .nav-cta {
  display: flex;
  flex-direction: column;
  margin-top: var(--space-4);
  padding-top: var(--space-4);
  border-top: 1px solid var(--border);
}

/* === Buttons === */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 26px;
  font-size: var(--font-size-md);
  font-weight: 600;
  border-radius: var(--radius-full);
  border: none;
  cursor: pointer;
  transition: var(--transition-fast);
  text-decoration: none;
  white-space: nowrap;
}

.btn:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

.btn-primary {
  background: var(--gradient-primary);
  color: #fff;
  box-shadow: 0 4px 16px rgba(79, 70, 229, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(79, 70, 229, 0.4);
}

.btn-primary:active {
  transform: translateY(0);
}

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

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

.btn-light {
  background: #fff;
  color: var(--primary);
  box-shadow: var(--shadow-sm);
}

.btn-light:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

.btn-lg {
  padding: 16px 34px;
  font-size: var(--font-size-lg);
}

.btn-sm {
  padding: 8px 18px;
  font-size: var(--font-size-sm);
}

/* === Hero === */
.hero {
  position: relative;
  padding-top: 160px;
  padding-bottom: var(--space-20);
  background: var(--gradient-hero);
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -100px;
  right: -150px;
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, rgba(79, 70, 229, 0.08) 0%, transparent 70%);
  border-radius: 50%;
  pointer-events: none;
}

.hero::after {
  content: '';
  position: absolute;
  bottom: -100px;
  left: -100px;
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, rgba(245, 158, 11, 0.06) 0%, transparent 70%);
  border-radius: 50%;
  pointer-events: none;
}

/* Cat ear decorations via CSS */
.hero-badge::before {
  content: '✨';
  margin-right: 6px;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 820px;
  margin: 0 auto;
  text-align: center;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(79, 70, 229, 0.08);
  color: var(--primary);
  padding: var(--space-2) var(--space-5);
  border-radius: var(--radius-full);
  font-size: var(--font-size-sm);
  font-weight: 500;
  margin-bottom: var(--space-6);
  border: 1px solid rgba(79, 70, 229, 0.12);
}

.hero-title {
  font-size: clamp(36px, 6vw, 64px);
  font-weight: 700;
  line-height: 1.15;
  color: var(--ink);
  margin-bottom: var(--space-6);
}

.hero-title .gradient-text {
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: 19px;
  color: var(--muted);
  line-height: 1.8;
  max-width: 600px;
  margin: 0 auto var(--space-8);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 16px;
  margin-bottom: var(--space-12);
}

.hero-illustration {
  max-width: 900px;
  margin: 0 auto;
  filter: drop-shadow(0 20px 40px rgba(79, 70, 229, 0.15));
}

/* === Platforms === */
.platforms {
  background: var(--bg-soft);
  padding: var(--space-12) 0;
}

.platforms-title {
  font-size: var(--font-size-xl);
  color: var(--muted);
  text-align: center;
  margin-bottom: var(--space-6);
}

.platforms-grid {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 14px;
}

.pill {
  padding: 10px 22px;
  background: #fff;
  border-radius: var(--radius-full);
  font-size: var(--font-size-md);
  font-weight: 500;
  color: var(--ink);
  border: 1px solid var(--border);
  box-shadow: var(--shadow-sm);
  transition: var(--transition-fast);
}

.pill:hover {
  border-color: var(--primary-light);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

/* === Features === */
.features {
  background: var(--bg);
}

.features-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 28px;
}

@media (min-width: 768px) {
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .features-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

.feature-card {
  background: var(--bg-card);
  border-radius: var(--radius-xl);
  padding: 32px;
  border: 1px solid var(--border);
  box-shadow: var(--shadow-sm);
  transition: var(--transition-base);
  position: relative;
  overflow: hidden;
}

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

.feature-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
  border-color: var(--primary-light);
}

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

.feature-icon {
  width: 56px;
  height: 56px;
  background: var(--gradient-primary);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--space-5);
}

.feature-icon svg {
  width: 28px;
  height: 28px;
  stroke: #fff;
  stroke-width: 1.5;
  fill: none;
}

.feature-card-title {
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--ink);
  margin-bottom: var(--space-3);
}

.feature-card-desc {
  font-size: 15px;
  color: var(--muted);
  line-height: 1.7;
}

/* === Roles === */
.roles {
  background: var(--bg-soft);
}

.roles-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 28px;
}

@media (min-width: 768px) {
  .roles-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .roles-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

.role-card {
  background: var(--bg-card);
  border-radius: var(--radius-xl);
  padding: 32px;
  border: 1px solid var(--border);
  box-shadow: var(--shadow-sm);
  transition: var(--transition-base);
  text-align: center;
}

.role-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--accent);
}

.role-icon {
  width: 64px;
  height: 64px;
  background: var(--accent-soft);
  border-radius: var(--radius-xl);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto var(--space-4);
  font-size: 28px;
}

.role-title {
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--ink);
  margin-bottom: var(--space-3);
}

.role-desc {
  font-size: 15px;
  color: var(--muted);
  line-height: 1.7;
}

/* === Spotlight === */
.spotlight {
  background: var(--bg);
  padding: var(--space-24) 0;
}

.spotlight .container {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-12);
  align-items: center;
}

@media (min-width: 768px) {
  .spotlight .container {
    grid-template-columns: 1fr 1fr;
  }
}

.spotlight-content {
  max-width: 480px;
}

.spotlight-visual {
  position: relative;
}

/* Pure CSS Mock Interview Chat UI */
.mock-chat {
  background: var(--bg-card);
  border-radius: var(--radius-xl);
  padding: var(--space-6);
  border: 1px solid var(--border);
  box-shadow: var(--shadow-lg);
  max-width: 400px;
  margin-left: auto;
}

.mock-chat-header {
  display: flex;
  align-items: center;
  gap: 12px;
  padding-bottom: var(--space-4);
  border-bottom: 1px solid var(--border);
  margin-bottom: var(--space-4);
}

.mock-avatar {
  width: 36px;
  height: 36px;
  background: var(--gradient-primary);
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-size: var(--font-size-sm);
  font-weight: 600;
}

.mock-chat-name {
  font-weight: 600;
  color: var(--ink);
}

.mock-chat-status {
  font-size: var(--font-size-xs);
  color: var(--success);
}

.mock-messages {
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

.mock-bubble {
  max-width: 85%;
  padding: 12px 16px;
  border-radius: var(--radius-lg);
  font-size: 14px;
  line-height: 1.6;
  animation: fadeInUp 0.3s ease forwards;
}

.mock-bubble.user {
  background: var(--gradient-primary);
  color: #fff;
  align-self: flex-end;
  border-bottom-right-radius: 4px;
}

.mock-bubble.ai {
  background: var(--bg-soft);
  color: var(--ink);
  align-self: flex-start;
  border-bottom-left-radius: 4px;
  border: 1px solid var(--border);
}

/* Waveform bars */
.waveform {
  display: flex;
  align-items: center;
  gap: 3px;
  padding: var(--space-4) 0;
  justify-content: center;
}

.waveform-bar {
  width: 3px;
  height: 16px;
  background: var(--primary);
  border-radius: 2px;
  transform-origin: center;
  animation: waveform 1s ease-in-out infinite;
}

.waveform-bar:nth-child(2) { animation-delay: 0.1s; }
.waveform-bar:nth-child(3) { animation-delay: 0.2s; }
.waveform-bar:nth-child(4) { animation-delay: 0.3s; }
.waveform-bar:nth-child(5) { animation-delay: 0.4s; }

@keyframes waveform {
  0%, 100% { transform: scaleY(1); opacity: 0.5; }
  50% { transform: scaleY(1.75); opacity: 1; }
}

.check-list {
  margin-top: var(--space-6);
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.check-item {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  font-size: var(--font-size-base);
  color: var(--ink);
}

.check-item::before {
  content: '✓';
  flex-shrink: 0;
  width: 22px;
  height: 22px;
  background: rgba(34, 197, 94, 0.1);
  color: var(--success);
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 12px;
  font-weight: 700;
}

/* === Testimonials === */
.testimonials {
  background: var(--gradient-hero);
}

.testimonials-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 28px;
}

@media (min-width: 900px) {
  .testimonials-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

.testimonial-card {
  background: var(--bg-card);
  border-radius: var(--radius-xl);
  padding: 28px;
  border: 1px solid var(--border);
  box-shadow: var(--shadow-sm);
  transition: var(--transition-base);
  position: relative;
}

.testimonial-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.testimonial-card::before {
  content: '"';
  position: absolute;
  top: 20px;
  right: 24px;
  font-size: 64px;
  font-weight: 700;
  color: var(--primary-light);
  opacity: 0.15;
  line-height: 1;
  font-family: Georgia, serif;
}

.testimonial-header {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: var(--space-4);
}

.avatar {
  width: 48px;
  height: 48px;
  background: var(--gradient-primary);
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-size: 18px;
  font-weight: 700;
  flex-shrink: 0;
}

.testimonial-name {
  font-size: var(--font-size-md);
  font-weight: 700;
  color: var(--ink);
}

.testimonial-role {
  font-size: var(--font-size-xs);
  color: var(--muted);
}

.testimonial-quote {
  font-size: 15px;
  line-height: 1.8;
  color: #475569;
}

/* === Stats === */
.stats {
  background: var(--gradient-primary);
  color: #fff;
  padding: var(--space-16) 0;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-8);
  text-align: center;
}

@media (min-width: 768px) {
  .stats-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

.stat-number {
  font-size: clamp(32px, 5vw, 48px);
  font-weight: 700;
  color: #fff;
  line-height: 1.2;
}

.stat-label {
  font-size: var(--font-size-sm);
  color: rgba(255, 255, 255, 0.8);
  margin-top: var(--space-2);
}

/* === FAQ === */
.faq {
  background: var(--bg);
}

.faq-list {
  max-width: 780px;
  margin: 0 auto;
}

.faq-item {
  background: var(--bg-card);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border);
  margin-bottom: 12px;
  overflow: hidden;
  transition: var(--transition-fast);
}

.faq-item.active {
  border-color: var(--primary);
  box-shadow: var(--shadow-md);
}

.faq-question {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  padding: 20px 24px;
  font-size: 17px;
  font-weight: 600;
  color: var(--ink);
  text-align: left;
  cursor: pointer;
  transition: var(--transition-fast);
  background: transparent;
  border: none;
}

.faq-question:hover {
  color: var(--primary);
}

.faq-question-icon {
  width: 24px;
  height: 24px;
  flex-shrink: 0;
  transition: transform var(--transition-base);
  color: var(--muted);
}

.faq-item.active .faq-question-icon {
  transform: rotate(180deg);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.35s ease;
}

.faq-item.active .faq-answer {
  max-height: 400px;
}

.faq-answer-inner {
  padding: 0 24px 20px;
  font-size: 15px;
  line-height: 1.8;
  color: var(--muted);
}

/* === CTA === */
.cta-section {
  background: var(--gradient-cta);
  color: #fff;
  border-radius: var(--radius-2xl);
  padding: var(--space-16) var(--space-8);
  text-align: center;
  position: relative;
  overflow: hidden;
}

.cta-section::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, rgba(255, 255, 255, 0.1) 0%, transparent 70%);
  border-radius: 50%;
  pointer-events: none;
}

.cta-title {
  font-size: clamp(28px, 4vw, 40px);
  font-weight: 700;
  margin-bottom: var(--space-4);
  position: relative;
}

.cta-subtitle {
  font-size: var(--font-size-lg);
  color: rgba(255, 255, 255, 0.9);
  margin-bottom: var(--space-8);
  max-width: 500px;
  margin-left: auto;
  margin-right: auto;
}

.cta-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 16px;
  margin-bottom: var(--space-8);
  position: relative;
}

.cta-checks {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 20px;
  position: relative;
}

.cta-checks span {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: var(--font-size-sm);
  color: rgba(255, 255, 255, 0.9);
}

.cta-checks span::before {
  content: '✓';
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 18px;
  height: 18px;
  background: rgba(255, 255, 255, 0.2);
  border-radius: var(--radius-full);
  font-size: 10px;
  font-weight: 700;
}

/* === Footer === */
.footer {
  background: var(--gradient-footer);
  color: #fff;
  padding: var(--space-16) 0 0;
}

.footer-top {
  padding-bottom: var(--space-12);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 40px;
}

@media (min-width: 600px) {
  .footer-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .footer-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

.footer-col-title {
  font-size: var(--font-size-md);
  font-weight: 700;
  color: #fff;
  margin-bottom: var(--space-4);
}

.footer-link {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: var(--font-size-sm);
  color: rgba(255, 255, 255, 0.7);
  padding: var(--space-2) 0;
  transition: var(--transition-fast);
}

.footer-link:hover {
  color: #fff;
}

.footer-contact {
  display: flex;
  flex-wrap: wrap;
  gap: 24px;
  margin-top: var(--space-4);
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding: var(--space-6) 0;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: var(--space-4);
}

.footer-bottom p {
  font-size: 13px;
  color: rgba(255, 255, 255, 0.5);
}

.footer-bottom-links {
  display: flex;
  gap: var(--space-5);
}

.footer-bottom-links a {
  font-size: 13px;
  color: rgba(255, 255, 255, 0.5);
  transition: var(--transition-fast);
}

.footer-bottom-links a:hover {
  color: #fff;
}

.social-icon {
  width: 36px;
  height: 36px;
  background: rgba(255, 255, 255, 0.1);
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition-fast);
}

.social-icon:hover {
  background: rgba(255, 255, 255, 0.2);
  transform: translateY(-2px);
}

.social-icon svg {
  width: 18px;
  height: 18px;
  fill: #fff;
}

/* === Modal / Toast === */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(15, 23, 42, 0.55);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: var(--z-modal);
  padding: 24px;
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
}

.modal-overlay.open {
  display: flex;
}

.modal {
  background: var(--bg-card);
  border-radius: var(--radius-xl);
  padding: 40px;
  max-width: 400px;
  width: 100%;
  text-align: center;
  position: relative;
  animation: scaleIn 0.25s ease;
  box-shadow: var(--shadow-xl);
}

@keyframes scaleIn {
  from {
    opacity: 0;
    transform: scale(0.95);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

.modal-icon {
  width: 56px;
  height: 56px;
  background: var(--gradient-primary);
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto var(--space-4);
}

.modal-icon svg {
  width: 28px;
  height: 28px;
  stroke: #fff;
  fill: none;
  stroke-width: 2;
}

.modal-title {
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--ink);
  margin-bottom: var(--space-3);
}

.modal-text {
  font-size: 15px;
  color: var(--muted);
  line-height: 1.7;
  margin-bottom: var(--space-6);
}

.modal-close {
  position: absolute;
  top: 16px;
  right: 16px;
  width: 32px;
  height: 32px;
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--muted);
  transition: var(--transition-fast);
  background: transparent;
}

.modal-close:hover {
  background: var(--bg-soft);
  color: var(--ink);
}

/* === Doc Pages === */
.page-hero {
  padding: 140px 0 60px;
  background: var(--gradient-hero);
}

.doc-title {
  text-align: center;
  font-size: clamp(32px, 5vw, 40px);
  font-weight: 700;
  color: #fff;
}

.doc-container {
  max-width: 860px;
  margin: 40px auto 100px;
  background: var(--bg-card);
  border-radius: var(--radius-2xl);
  padding: 48px;
  border: 1px solid var(--border);
  box-shadow: var(--shadow-md);
}

.doc-meta {
  font-size: var(--font-size-sm);
  color: var(--muted);
  margin-bottom: var(--space-7);
  padding-bottom: var(--space-4);
  border-bottom: 1px solid var(--border);
}

.doc-intro {
  font-size: var(--font-size-md);
  line-height: 1.9;
  color: var(--ink);
  margin-bottom: var(--space-8);
}

.doc-chapter {
  margin: var(--space-8) 0;
}

.doc-chapter-title {
  font-size: 22px;
  font-weight: 700;
  color: var(--ink);
  margin-bottom: var(--space-4);
  padding-left: 16px;
  border-left: 4px solid var(--primary);
}

.doc-list {
  padding-left: 22px;
  list-style: decimal;
}

.nowrap {
  white-space: nowrap;
}

.doc-list li {
  font-size: 15px;
  line-height: 1.9;
  margin-bottom: 8px;
  color: var(--ink);
  padding-left: 4px;
}

.doc-strong {
  font-weight: 700;
  color: var(--primary);
}

/* === Scroll Animation === */
.animate-in {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.animate-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Staggered animation delays */
.animate-in:nth-child(2) { transition-delay: 0.1s; }
.animate-in:nth-child(3) { transition-delay: 0.2s; }
.animate-in:nth-child(4) { transition-delay: 0.3s; }
.animate-in:nth-child(5) { transition-delay: 0.4s; }
.animate-in:nth-child(6) { transition-delay: 0.5s; }

/* Base keyframe for chat bubbles */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* === Accessibility === */
:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

/* Skip to content link */
.skip-to-content,
.skip-link {
  position: absolute;
  top: -100%;
  left: 50%;
  transform: translateX(-50%);
  background: var(--primary);
  color: #fff;
  padding: var(--space-3) var(--space-6);
  border-radius: 0 0 var(--radius-md) var(--radius-md);
  font-weight: 600;
  z-index: var(--z-skip);
  transition: top var(--transition-fast);
}

.skip-to-content:focus,
.skip-link:focus {
  top: 0;
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  
  html {
    scroll-behavior: auto;
  }
  
  .animate-in {
    opacity: 1;
    transform: none;
    transition: none;
  }
}

/* === Responsive Utilities === */
@media (max-width: 767px) {
  .section {
    padding: var(--space-16) 0;
  }
  
  .section-title {
    font-size: clamp(24px, 6vw, 32px);
  }
  
  .hero {
    padding-top: 120px;
  }
  
  .hero-title {
    font-size: clamp(28px, 8vw, 40px);
  }
  
  .hero-subtitle {
    font-size: 16px;
  }
  
  .container {
    padding: 0 16px;
  }
  
  .stats-grid {
    gap: var(--space-6);
  }
  
  .doc-container {
    padding: var(--space-6);
    margin-left: 16px;
    margin-right: 16px;
  }
}

/* Prevent horizontal overflow at 375px */
@media (max-width: 375px) {
  html {
    overflow-x: hidden;
  }
  
  body {
    overflow-x: hidden;
  }
  
  .hero-actions {
    flex-direction: column;
    align-items: stretch;
  }
  
  .btn {
    justify-content: center;
  }
}

/* Large desktop */
@media (min-width: 1200px) {
  .container {
    padding: 0 32px;
  }
}

/* ================================================================
   Mobile Hardening — 移动端响应式强化
   T6–T12: 按钮堆叠 / mock居中 / menu穿透 / safe-area / 触控目标 / 极窄屏 / footer
   ================================================================ */

/* T6: hero-actions / cta-actions 按钮窄屏堆叠
   ≤767px 区间两个 btn-lg 并排过挤，改为纵向堆叠并拉满宽度 */
@media (max-width: 767px) {
  .hero-actions,
  .cta-actions {
    flex-direction: column;
    align-items: stretch;
    gap: 12px;
  }

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

/* T7: mock-chat 手机端居中
   原 max-width:400px + margin-left:auto 导致 <768px 单列时右对齐，
   改为水平居中并允许占满容器宽度 */
@media (max-width: 767px) {
  .mock-chat {
    margin-left: auto;
    margin-right: auto;
    max-width: 100%;
  }
}

/* T8: mobile-menu 撑满视口剩余部分，消除下方内容穿透
   position:fixed + top:68px + bottom:0 使菜单从 navbar 下方延伸到视口底部
   安全区设备上 T9 的 top 会自动参与计算，无需额外处理
   内容垂直居中避免全屏菜单底部大留白 */
@media (max-width: 767px) {
  .mobile-menu.open {
    bottom: 0;
    justify-content: center;
  }
}

/* T9: safe-area-inset 适配 iPhone 刘海 / 底部横条
   仅在支持 env(safe-area-inset-top) 的设备生效，桌面零副作用 */
@supports (padding-top: env(safe-area-inset-top)) {
  .navbar {
    padding-top: env(safe-area-inset-top);
  }

  /* navbar 内部内容需要下移补偿，保持 68px 内部高度不变 */
  .navbar-inner {
    height: calc(68px + env(safe-area-inset-top));
  }

  /* mobile-menu 从 navbar 下方展开，需同步下移 */
  .mobile-menu {
    top: calc(68px + env(safe-area-inset-top));
  }

  /* footer 底部安全区内边距 */
  .footer {
    padding-bottom: env(safe-area-inset-bottom);
  }
}

/* T10: 触控目标 44px 最小高度
   仅对真触摸设备（pointer: coarse）生效，桌面端不受影响 */
@media (pointer: coarse) {
  .btn,
  .nav-link,
  .hamburger,
  .faq-question,
  .mobile-menu a,
  .modal-close,
  .footer-link {
    min-height: 44px;
  }
}

/* T11: 320px 极窄屏防破版
   覆盖 320px 设备，收紧间距和字号，确保无横向滚动 */
@media (max-width: 360px) {
  .container {
    padding: 0 12px;
  }

  .hero-title {
    font-size: clamp(26px, 7vw, 32px);
  }

  .hero-badge {
    font-size: 12px;
    padding: 6px 14px;
  }

  .pill {
    padding: 8px 14px;
    font-size: 13px;
  }

  .feature-card,
  .role-card,
  .testimonial-card {
    padding: 24px;
  }

  .mock-chat {
    padding: var(--space-4);
  }

  /* 确保固定宽度元素不溢出 320px */
  .hero-illustration {
    max-width: 100%;
  }

  .cta-section {
    padding: var(--space-8) var(--space-4);
    border-radius: var(--radius-lg);
  }
}

/* T12: footer-bottom 窄屏居中
   ≤600px 时版权行和链接改为居中排列，整洁美观 */
@media (max-width: 600px) {
  .footer-bottom {
    justify-content: center;
    text-align: center;
  }

  .footer-bottom-links {
    justify-content: center;
  }
}

/* Print styles */
@media print {
  .navbar,
  .hamburger,
  .mobile-menu,
  .cta-section,
  .footer {
    display: none !important;
  }
  
  .section {
    padding: 24px 0;
    page-break-inside: avoid;
  }
  
  body {
    font-size: 12pt;
    color: #000;
  }
}