/* ============================================
   AI 出海灵感看板 — Design System
   Aesthetic: Editorial Utility
   Colors: Warm neutrals + deep teal accent
   No gradients.
   ============================================ */

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

:root {
  /* Color System */
  --color-bg: #FAFAF8;
  --color-surface: #FFFFFF;
  --color-surface-alt: #F5F4F1;
  --color-border: #E5E3DF;
  --color-border-light: #EEEDEA;
  --color-text: #1A1A1A;
  --color-text-secondary: #6B6B6B;
  --color-text-tertiary: #9A9A9A;
  --color-accent: #0D7C66;
  --color-accent-light: #E8F5F1;
  --color-accent-dark: #0A6352;
  --color-tag-bg: #F3F2EF;
  --color-tag-text: #555555;
  --color-easy: #1B7D40;
  --color-easy-bg: #E9F7EF;
  --color-medium: #B06D16;
  --color-medium-bg: #FDF3E3;
  --color-hard: #B9402E;
  --color-hard-bg: #FDECEC;
  --color-low: #1B7D40;
  --color-mid: #B06D16;
  --color-high: #B9402E;

  /* Typography */
  --font-display: 'Newsreader', 'Georgia', 'Noto Serif SC', serif;
  --font-body: -apple-system, BlinkMacSystemFont, 'PingFang SC', 'Hiragino Sans GB', 'Noto Sans SC', 'Microsoft YaHei', 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', 'Fira Code', 'Consolas', monospace;

  /* Type Scale */
  --text-display: 3rem;
  --text-h1: 2.25rem;
  --text-h2: 1.75rem;
  --text-h3: 1.25rem;
  --text-body: 1rem;
  --text-small: 0.875rem;
  --text-caption: 0.75rem;

  /* Spacing */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;

  /* Layout */
  --max-width: 1200px;
  --nav-height: 64px;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow-md: 0 2px 8px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 4px 16px rgba(0, 0, 0, 0.08);
}

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

body {
  font-family: var(--font-body);
  color: var(--color-text);
  background-color: var(--color-bg);
  line-height: 1.7;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main {
  flex: 1;
}

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

a:hover {
  color: var(--color-accent-dark);
}

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

ul, ol {
  list-style: none;
}

/* --- Utilities --- */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-6);
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* --- Typography --- */
h1, h2, h3, h4 {
  line-height: 1.3;
  font-weight: 700;
  color: var(--color-text);
}

h1 { font-size: var(--text-h1); }
h2 { font-size: var(--text-h2); }
h3 { font-size: var(--text-h3); }

.display-heading {
  font-family: var(--font-display);
  font-size: var(--text-display);
  font-weight: 500;
  letter-spacing: -0.02em;
  line-height: 1.15;
}

.section-label {
  font-size: var(--text-caption);
  font-family: var(--font-mono);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-tertiary);
  margin-bottom: var(--space-3);
}

/* --- Navigation --- */
.site-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(250, 250, 248, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border-light);
  height: var(--nav-height);
}

.site-nav .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  color: var(--color-text);
  font-weight: 700;
  font-size: 1.1rem;
  text-decoration: none;
}

.nav-brand:hover {
  color: var(--color-text);
}

.nav-brand-icon {
  width: 32px;
  height: 32px;
  background: var(--color-accent);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
}

.nav-brand-icon svg {
  width: 18px;
  height: 18px;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-1);
}

.nav-links a {
  color: var(--color-text-secondary);
  font-size: var(--text-small);
  padding: var(--space-2) var(--space-3);
  border-radius: 6px;
  transition: all var(--transition-fast);
  font-weight: 500;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--color-text);
  background: var(--color-surface-alt);
}

.nav-links a.active {
  color: var(--color-accent);
}

/* Mobile nav toggle */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  padding: var(--space-2);
  cursor: pointer;
  color: var(--color-text);
}

.nav-toggle svg {
  width: 24px;
  height: 24px;
}

/* --- Hero --- */
.hero {
  padding: var(--space-24) 0 var(--space-16);
  text-align: center;
}

.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-caption);
  color: var(--color-accent);
  background: var(--color-accent-light);
  padding: var(--space-1) var(--space-3);
  border-radius: 20px;
  margin-bottom: var(--space-6);
  letter-spacing: 0.04em;
}

.hero .display-heading {
  max-width: 720px;
  margin: 0 auto var(--space-6);
}

.hero-description {
  font-size: 1.125rem;
  color: var(--color-text-secondary);
  max-width: 560px;
  margin: 0 auto var(--space-10);
  line-height: 1.8;
}

.hero-actions {
  display: flex;
  gap: var(--space-4);
  justify-content: center;
  flex-wrap: wrap;
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-6);
  border-radius: 8px;
  font-size: var(--text-small);
  font-weight: 600;
  font-family: var(--font-body);
  cursor: pointer;
  transition: all var(--transition-fast);
  border: 1px solid transparent;
  text-decoration: none;
  line-height: 1.4;
}

.btn-primary {
  background: var(--color-accent);
  color: white;
  border-color: var(--color-accent);
}

.btn-primary:hover {
  background: var(--color-accent-dark);
  border-color: var(--color-accent-dark);
  color: white;
}

.btn-secondary {
  background: var(--color-surface);
  color: var(--color-text);
  border-color: var(--color-border);
}

.btn-secondary:hover {
  border-color: var(--color-text-tertiary);
  background: var(--color-surface-alt);
  color: var(--color-text);
}

/* --- Stats Bar --- */
.stats-bar {
  display: flex;
  justify-content: center;
  gap: var(--space-12);
  padding: var(--space-10) 0;
  border-top: 1px solid var(--color-border-light);
  border-bottom: 1px solid var(--color-border-light);
  margin: var(--space-12) 0;
}

.stat-item {
  text-align: center;
}

.stat-number {
  font-family: var(--font-display);
  font-size: var(--text-h1);
  font-weight: 500;
  color: var(--color-text);
  display: block;
  line-height: 1.2;
}

.stat-label {
  font-size: var(--text-small);
  color: var(--color-text-secondary);
  margin-top: var(--space-1);
  display: block;
}

/* --- Section --- */
.section {
  padding: var(--space-16) 0;
}

.section-header {
  margin-bottom: var(--space-10);
}

.section-header h2 {
  margin-bottom: var(--space-2);
}

.section-header p {
  color: var(--color-text-secondary);
  max-width: 560px;
}

.section-header--center {
  text-align: center;
}

.section-header--center p {
  margin: 0 auto;
}

/* --- Card Grid --- */
.card-grid {
  display: grid;
  gap: var(--space-6);
}

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

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

/* --- Idea Card --- */
.idea-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: var(--space-6);
  transition: all var(--transition-base);
  display: flex;
  flex-direction: column;
}

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

.idea-card-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: var(--space-3);
  margin-bottom: var(--space-3);
}

.idea-card-icon {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  background: var(--color-surface-alt);
  color: var(--color-accent);
}

.idea-card-icon svg {
  width: 20px;
  height: 20px;
}

.idea-card h3 {
  font-size: var(--text-h3);
  margin-bottom: var(--space-2);
}

.idea-card-description {
  font-size: var(--text-small);
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: var(--space-4);
  flex: 1;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.idea-card-meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-bottom: var(--space-4);
}

.idea-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: var(--space-4);
  border-top: 1px solid var(--color-border-light);
  font-size: var(--text-small);
}

.idea-card-footer-item {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  color: var(--color-text-secondary);
}

/* --- Tags --- */
.tag {
  display: inline-flex;
  align-items: center;
  padding: var(--space-1) var(--space-2);
  border-radius: 4px;
  font-size: var(--text-caption);
  font-family: var(--font-mono);
  font-weight: 500;
  white-space: nowrap;
}

.tag--category {
  background: var(--color-tag-bg);
  color: var(--color-tag-text);
}

.tag--easy {
  background: var(--color-easy-bg);
  color: var(--color-easy);
}

.tag--medium {
  background: var(--color-medium-bg);
  color: var(--color-medium);
}

.tag--hard {
  background: var(--color-hard-bg);
  color: var(--color-hard);
}

.tag--market {
  background: var(--color-accent-light);
  color: var(--color-accent);
}

/* --- Category Card --- */
.category-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: var(--space-6);
  text-align: center;
  transition: all var(--transition-base);
  cursor: pointer;
  text-decoration: none;
  color: var(--color-text);
  display: block;
}

.category-card:hover {
  border-color: var(--color-accent);
  color: var(--color-text);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.category-card-icon {
  margin-bottom: var(--space-3);
  display: inline-flex;
  width: 40px;
  height: 40px;
  align-items: center;
  justify-content: center;
  border-radius: 10px;
  background: var(--color-surface-alt);
  color: var(--color-accent);
}

.category-card-icon svg {
  width: 22px;
  height: 22px;
}

.category-card h3 {
  font-size: var(--text-body);
  margin-bottom: var(--space-1);
}

.category-card p {
  font-size: var(--text-small);
  color: var(--color-text-secondary);
  line-height: 1.6;
  min-height: 2.8em;
}

/* --- Filter Bar --- */
.filter-bar {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: var(--space-5);
  margin-bottom: var(--space-8);
}

.filter-bar-top {
  display: flex;
  gap: var(--space-4);
  margin-bottom: var(--space-4);
}

.search-input-wrap {
  flex: 1;
  position: relative;
}

.search-input-wrap svg {
  position: absolute;
  left: var(--space-3);
  top: 50%;
  transform: translateY(-50%);
  width: 18px;
  height: 18px;
  color: var(--color-text-tertiary);
  pointer-events: none;
}

.search-input {
  width: 100%;
  padding: var(--space-3) var(--space-3) var(--space-3) var(--space-10);
  border: 1px solid var(--color-border);
  border-radius: 8px;
  font-size: var(--text-small);
  font-family: var(--font-body);
  color: var(--color-text);
  background: var(--color-bg);
  transition: border-color var(--transition-fast);
}

.search-input::placeholder {
  color: var(--color-text-tertiary);
}

.search-input:focus {
  outline: none;
  border-color: var(--color-accent);
}

.filter-groups {
  display: flex;
  gap: var(--space-6);
  flex-wrap: wrap;
}

.filter-group {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.filter-group-label {
  font-size: var(--text-caption);
  font-family: var(--font-mono);
  color: var(--color-text-tertiary);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  white-space: nowrap;
}

.filter-pills {
  display: flex;
  gap: var(--space-1);
  flex-wrap: wrap;
}

.filter-pill {
  padding: var(--space-1) var(--space-3);
  border-radius: 20px;
  font-size: var(--text-caption);
  font-family: var(--font-body);
  font-weight: 500;
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.filter-pill:hover {
  border-color: var(--color-text-tertiary);
  color: var(--color-text);
}

.filter-pill.active {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: white;
}

.results-count {
  font-size: var(--text-small);
  color: var(--color-text-tertiary);
  margin-bottom: var(--space-6);
}

.results-count strong {
  color: var(--color-text);
}

/* --- Page Header --- */
.page-header {
  padding: var(--space-16) 0 var(--space-10);
  border-bottom: 1px solid var(--color-border-light);
  margin-bottom: var(--space-10);
}

.page-header h1 {
  margin-bottom: var(--space-3);
}

.page-header p {
  font-size: 1.1rem;
  color: var(--color-text-secondary);
  max-width: 640px;
  line-height: 1.8;
}

/* --- Playbook Card --- */
.playbook-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  overflow: hidden;
  transition: all var(--transition-base);
}

.playbook-card:hover {
  box-shadow: var(--shadow-md);
}

.playbook-card-header {
  padding: var(--space-6) var(--space-8);
  cursor: pointer;
  display: flex;
  align-items: flex-start;
  gap: var(--space-5);
  transition: background var(--transition-fast);
}

.playbook-card-header:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: -2px;
  background: var(--color-surface-alt);
}

.playbook-card-header:hover {
  background: var(--color-surface-alt);
}

.playbook-number {
  font-family: var(--font-display);
  font-size: var(--text-h1);
  font-weight: 400;
  color: var(--color-accent);
  line-height: 1;
  flex-shrink: 0;
  width: 48px;
}

.playbook-card-info {
  flex: 1;
}

.playbook-card-info h3 {
  font-size: var(--text-h3);
  margin-bottom: var(--space-2);
}

.playbook-card-info p {
  font-size: var(--text-small);
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.playbook-card-meta {
  display: flex;
  gap: var(--space-3);
  margin-top: var(--space-3);
}

.playbook-toggle {
  width: 32px;
  height: 32px;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  background: var(--color-surface);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-fast);
  flex-shrink: 0;
  align-self: center;
  color: var(--color-text-secondary);
}

.playbook-toggle:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

.playbook-toggle svg {
  width: 16px;
  height: 16px;
  transition: transform var(--transition-base);
}

.playbook-card.open .playbook-toggle svg {
  transform: rotate(180deg);
}

.playbook-card-body {
  max-height: 0;
  overflow: hidden;
  transition: max-height 400ms ease;
}

.playbook-card.open .playbook-card-body {
  max-height: 2000px;
}

.playbook-card-content {
  padding: 0 var(--space-8) var(--space-8);
  padding-left: calc(var(--space-8) + 48px + var(--space-5));
  border-top: 1px solid var(--color-border-light);
}

.playbook-card-content h4 {
  font-size: var(--text-body);
  font-weight: 600;
  margin: var(--space-6) 0 var(--space-3);
  color: var(--color-text);
}

.playbook-card-content h4:first-child {
  margin-top: var(--space-6);
}

.playbook-card-content ol,
.playbook-card-content ul {
  padding-left: var(--space-5);
}

.playbook-card-content ol {
  list-style: decimal;
}

.playbook-card-content ul {
  list-style: disc;
}

.playbook-card-content li {
  font-size: var(--text-small);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-2);
  line-height: 1.7;
}

.playbook-card-content li strong {
  color: var(--color-text);
}

.playbook-tip {
  background: var(--color-accent-light);
  border-left: 3px solid var(--color-accent);
  padding: var(--space-4) var(--space-5);
  border-radius: 0 8px 8px 0;
  margin-top: var(--space-4);
}

.playbook-tip p {
  font-size: var(--text-small);
  color: var(--color-accent-dark);
  line-height: 1.7;
}

/* --- CTA Section --- */
.cta-section {
  background: var(--color-surface-alt);
  border-top: 1px solid var(--color-border-light);
  border-bottom: 1px solid var(--color-border-light);
  padding: var(--space-16) 0;
  text-align: center;
}

.cta-section h2 {
  margin-bottom: var(--space-3);
}

.cta-section p {
  color: var(--color-text-secondary);
  margin-bottom: var(--space-8);
  max-width: 480px;
  margin-left: auto;
  margin-right: auto;
}

/* --- Footer --- */
.site-footer {
  border-top: 1px solid var(--color-border-light);
  padding: var(--space-10) 0;
  margin-top: auto;
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.footer-copy {
  font-size: var(--text-small);
  color: var(--color-text-tertiary);
}

.footer-links {
  display: flex;
  gap: var(--space-6);
}

.footer-links a {
  font-size: var(--text-small);
  color: var(--color-text-tertiary);
  transition: color var(--transition-fast);
}

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

/* --- Empty State --- */
.empty-state {
  text-align: center;
  padding: var(--space-16) 0;
  color: var(--color-text-secondary);
}

.empty-state-icon {
  margin-bottom: var(--space-4);
  opacity: 0.5;
  display: inline-flex;
}

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

.empty-state h3 {
  color: var(--color-text-secondary);
  margin-bottom: var(--space-2);
}

.empty-state p {
  font-size: var(--text-small);
}

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

.animate-in {
  animation: fadeInUp 500ms ease both;
}

.animate-in:nth-child(1) { animation-delay: 0ms; }
.animate-in:nth-child(2) { animation-delay: 60ms; }
.animate-in:nth-child(3) { animation-delay: 120ms; }
.animate-in:nth-child(4) { animation-delay: 180ms; }
.animate-in:nth-child(5) { animation-delay: 240ms; }
.animate-in:nth-child(6) { animation-delay: 300ms; }
.animate-in:nth-child(7) { animation-delay: 360ms; }
.animate-in:nth-child(8) { animation-delay: 420ms; }
.animate-in:nth-child(9) { animation-delay: 480ms; }

/* --- Responsive --- */
@media (max-width: 1024px) {
  .card-grid--3 {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  :root {
    --text-display: 2.25rem;
    --text-h1: 1.75rem;
    --text-h2: 1.5rem;
    --nav-height: 56px;
  }

  .container {
    padding: 0 var(--space-4);
  }

  /* Mobile nav */
  .nav-toggle {
    display: flex;
    align-items: center;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    flex-direction: column;
    padding: var(--space-4);
    gap: var(--space-1);
  }

  .nav-links.open {
    display: flex;
  }

  .nav-links a {
    width: 100%;
    padding: var(--space-3) var(--space-4);
  }

  .site-nav .container {
    position: relative;
  }

  /* Hero */
  .hero {
    padding: var(--space-16) 0 var(--space-10);
  }

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

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

  /* Stats */
  .stats-bar {
    gap: var(--space-6);
    flex-wrap: wrap;
    justify-content: space-around;
    padding: var(--space-8) var(--space-4);
  }

  .stat-item {
    min-width: 96px;
  }

  .stat-number {
    font-size: var(--text-h2);
  }

  /* Cards */
  .card-grid--3,
  .card-grid--2 {
    grid-template-columns: 1fr;
  }

  /* Filter */
  .filter-bar-top {
    flex-direction: column;
  }

  .filter-groups {
    flex-direction: column;
    gap: var(--space-3);
  }

  .filter-group {
    flex-wrap: wrap;
  }

  /* Playbook */
  .playbook-card-header {
    padding: var(--space-5);
    gap: var(--space-3);
  }

  .playbook-number {
    font-size: var(--text-h2);
    width: 36px;
  }

  .playbook-card-content {
    padding: 0 var(--space-5) var(--space-5);
    padding-left: var(--space-5);
  }

  /* Footer */
  .footer-inner {
    flex-direction: column;
    gap: var(--space-4);
    text-align: center;
  }

  /* Page header */
  .page-header {
    padding: var(--space-10) 0 var(--space-6);
    margin-bottom: var(--space-6);
  }
}

@media (max-width: 480px) {
  :root {
    --text-display: 1.875rem;
    --text-h1: 1.5rem;
  }

  .stats-bar {
    gap: var(--space-4);
  }

  .stat-item {
    flex: 1;
    min-width: 80px;
  }

  .filter-pills {
    gap: var(--space-1);
  }
}

/* --- Focus Styles (Accessibility) --- */
:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

button:focus-visible,
a:focus-visible,
input:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

/* --- Print --- */
@media print {
  .site-nav,
  .site-footer,
  .filter-bar,
  .hero-actions,
  .cta-section {
    display: none;
  }

  body {
    color: #000;
    background: #fff;
  }

  .idea-card {
    break-inside: avoid;
    border: 1px solid #ccc;
  }
}