/* 
 * Mahua Word Embeddings - Black & White Professional Theme
 * CSS Variables for consistent styling
 */

:root {
  --color-black: #000000;
  --color-white: #ffffff;
  --color-gray-100: #f5f5f5;
  --color-gray-200: #e5e5e5;
  --color-gray-300: #d4d4d4;
  --color-gray-400: #a3a3a3;
  --color-gray-500: #737373;
  --color-gray-600: #525252;
  --color-gray-700: #404040;
  --color-gray-800: #262626;
  --color-gray-900: #171717;
  
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Noto Sans SC", "Microsoft JhengHei", sans-serif;
  --font-mono: "SF Mono", "Fira Code", "Consolas", monospace;
  
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  
  --max-width: 800px;
  --border-radius: 4px;
  --transition-fast: 0.15s ease;
  --transition-normal: 0.25s ease;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.7;
  color: var(--color-black);
  background-color: var(--color-white);
  -webkit-font-smoothing: antialiased;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.3;
  margin-bottom: var(--spacing-md);
}

h1 {
  font-size: 2rem;
  letter-spacing: -0.02em;
}

h2 {
  font-size: 1.5rem;
  padding-bottom: var(--spacing-sm);
  border-bottom: 2px solid var(--color-black);
}

h3 {
  font-size: 1.125rem;
}

p {
  margin-bottom: var(--spacing-md);
}

a {
  color: var(--color-black);
  text-decoration: underline;
  text-underline-offset: 2px;
  transition: opacity var(--transition-fast);
}

a:hover {
  opacity: 0.7;
}

/* Navigation */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background-color: var(--color-white);
  border-bottom: 1px solid var(--color-gray-200);
  z-index: 1000;
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-md);
  display: flex;
  align-items: center;
  height: 60px;
}

.nav-logo {
  font-weight: 700;
  font-size: 1.125rem;
  text-decoration: none;
  margin-right: var(--spacing-xl);
}

.nav-logo:hover {
  opacity: 1;
}

.nav-links {
  display: flex;
  gap: var(--spacing-lg);
  list-style: none;
}

.nav-links a {
  text-decoration: none;
  font-size: 0.9rem;
  padding: var(--spacing-sm) 0;
  position: relative;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--color-black);
  transition: width var(--transition-normal);
}

.nav-links a:hover::after,
.nav-links a.active::after {
  width: 100%;
}

.nav-links a.active {
  font-weight: 600;
}

/* Main Content */
.main {
  padding-top: 80px;
  min-height: 100vh;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--spacing-xl) var(--spacing-md);
}

/* Hero Section */
.hero {
  text-align: center;
  padding: var(--spacing-2xl) 0;
}

.hero h1 {
  font-size: 2.5rem;
  margin-bottom: var(--spacing-md);
}

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--color-gray-600);
  margin-bottom: var(--spacing-xl);
}

/* Stats Grid */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-2xl);
}

.stat-card {
  padding: var(--spacing-lg);
  border: 1px solid var(--color-gray-300);
  text-align: center;
  transition: border-color var(--transition-fast);
}

.stat-card:hover {
  border-color: var(--color-black);
}

.stat-number {
  font-size: 2rem;
  font-weight: 700;
  display: block;
}

.stat-label {
  font-size: 0.875rem;
  color: var(--color-gray-600);
  margin-top: var(--spacing-xs);
}

/* Cards */
.card {
  border: 1px solid var(--color-gray-300);
  padding: var(--spacing-lg);
  margin-bottom: var(--spacing-lg);
  transition: border-color var(--transition-fast);
}

.card:hover {
  border-color: var(--color-black);
}

.card-title {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: var(--spacing-sm);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.card-content {
  color: var(--color-gray-700);
  font-size: 0.95rem;
}

/* Buttons */
.btn {
  display: inline-block;
  padding: var(--spacing-sm) var(--spacing-lg);
  background-color: var(--color-black);
  color: var(--color-white);
  text-decoration: none;
  font-size: 0.875rem;
  font-weight: 500;
  border: none;
  cursor: pointer;
  transition: opacity var(--transition-fast);
  border-radius: var(--border-radius);
}

.btn:hover {
  opacity: 0.8;
  color: var(--color-white);
  text-decoration: none;
}

.btn-outline {
  background-color: transparent;
  color: var(--color-black);
  border: 1px solid var(--color-black);
}

.btn-outline:hover {
  background-color: var(--color-black);
  color: var(--color-white);
}

.btn-small {
  padding: var(--spacing-xs) var(--spacing-md);
  font-size: 0.8rem;
}

/* Year Tabs */
.year-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-xl);
  padding-bottom: var(--spacing-md);
  border-bottom: 1px solid var(--color-gray-200);
}

.year-tab {
  padding: var(--spacing-sm) var(--spacing-md);
  background: transparent;
  border: 1px solid var(--color-gray-300);
  cursor: pointer;
  font-size: 0.9rem;
  transition: all var(--transition-fast);
  border-radius: var(--border-radius);
}

.year-tab:hover {
  border-color: var(--color-black);
}

.year-tab.active {
  background-color: var(--color-black);
  color: var(--color-white);
  border-color: var(--color-black);
}

/* Tables */
.table-wrapper {
  overflow-x: auto;
  margin-bottom: var(--spacing-lg);
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}

th, td {
  padding: var(--spacing-sm) var(--spacing-md);
  text-align: left;
  border-bottom: 1px solid var(--color-gray-200);
}

th {
  font-weight: 600;
  background-color: var(--color-gray-100);
}

tr:hover {
  background-color: var(--color-gray-100);
}

/* Expandable Section */
.expandable {
  border: 1px solid var(--color-gray-300);
  margin-bottom: var(--spacing-md);
  overflow: hidden;
}

.expandable-header {
  padding: var(--spacing-md);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-weight: 500;
  transition: background-color var(--transition-fast);
}

.expandable-header:hover {
  background-color: var(--color-gray-100);
}

.expandable-icon {
  transition: transform var(--transition-normal);
}

.expandable.open .expandable-icon {
  transform: rotate(180deg);
}

.expandable-content {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--normal);
}

.expandable.open .expandable-content {
  max-height: 10000px;
}

.expandable-body {
  padding: var(--spacing-md);
  border-top: 1px solid var(--color-gray-200);
  background-color: var(--color-gray-100);
}

/* Concept Grid */
.concept-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-xl);
}

.concept-card {
  padding: var(--spacing-md);
  border: 1px solid var(--color-gray-300);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.concept-card:hover,
.concept-card.active {
  border-color: var(--color-black);
  background-color: var(--color-gray-100);
}

.concept-chinese {
  font-size: 1.5rem;
  font-weight: 600;
  margin-bottom: var(--spacing-xs);
}

.concept-english {
  font-size: 0.875rem;
  color: var(--color-gray-600);
}

/* Method List */
.method-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-lg);
}

.method-item {
  padding: var(--spacing-sm) var(--spacing-md);
  border: 1px solid var(--color-gray-300);
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  cursor: pointer;
  font-size: 0.9rem;
}

.method-item:hover {
  border-color: var(--color-gray-500);
}

.method-item.active {
  background-color: var(--color-black);
  color: var(--color-white);
  border-color: var(--color-black);
}

.method-checkbox {
  width: 16px;
  height: 16px;
  border: 2px solid currentColor;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.method-item.active .method-checkbox::after {
  content: '✓';
  font-size: 12px;
}

/* Code Block */
pre, code {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  background-color: var(--color-gray-100);
  overflow-x: auto;
}

code {
  padding: 0.125rem 0.25rem;
  border-radius: 2px;
}

pre {
  padding: var(--spacing-md);
  border: 1px solid var(--color-gray-300);
  margin-bottom: var(--spacing-md);
}

pre code {
  background: none;
  padding: 0;
}

/* Download Section */
.download-section {
  margin-bottom: var(--spacing-xl);
}

.download-group {
  margin-bottom: var(--spacing-lg);
}

.download-group-title {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: var(--spacing-md);
  padding-bottom: var(--spacing-sm);
  border-bottom: 1px solid var(--color-gray-300);
}

.download-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-sm) 0;
  border-bottom: 1px solid var(--color-gray-200);
}

.download-item:last-child {
  border-bottom: none;
}

.download-info {
  flex: 1;
}

.download-name {
  font-weight: 500;
}

.download-meta {
  font-size: 0.8rem;
  color: var(--color-gray-500);
  margin-top: var(--spacing-xs);
}

/* Footer */
.footer {
  border-top: 1px solid var(--color-gray-200);
  padding: var(--spacing-xl) 0;
  margin-top: var(--spacing-2xl);
  text-align: center;
  font-size: 0.875rem;
  color: var(--color-gray-600);
}

/* Utility Classes */
.text-center {
  text-align: center;
}

.text-gray {
  color: var(--color-gray-600);
}

.text-small {
  font-size: 0.875rem;
}

.mt-lg {
  margin-top: var(--spacing-lg);
}

.mb-lg {
  margin-bottom: var(--spacing-lg);
}

.mb-xl {
  margin-bottom: var(--spacing-xl);
}

.flex {
  display: flex;
}

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

.gap-sm {
  gap: var(--spacing-sm);
}

.gap-md {
  gap: var(--spacing-md);
}

/* Responsive */
@media (max-width: 600px) {
  .nav-container {
    flex-direction: column;
    height: auto;
    padding: var(--spacing-md);
  }

  .nav-links {
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--spacing-sm);
  }

  .nav-logo {
    margin-right: 0;
    margin-bottom: var(--spacing-sm);
  }

  .hero h1 {
    font-size: 1.75rem;
  }

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

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

/* Print Styles */
@media print {
  .nav {
    display: none;
  }

  .main {
    padding-top: 0;
  }

  a {
    text-decoration: none;
  }
}