/* Google Fonts - 中英文统一字体方案 */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=Noto+Sans+SC:wght@300;400;500;700&display=swap');

/**
 * LocalCN Trip - CSS Design System
 * Version: 1.0.0
 * Author: FullstackArchitect
 *
 * 设计令牌（Design Tokens）和组件库
 * 支持亮色/暗色/系统主题
 */

/* ==========================================
   1. 设计令牌（Design Tokens）
   ========================================== */

/* 主题无关令牌 */
:root {
  /* 字体系统 */
  --font-sans: 'Inter', 'Noto Sans SC', system-ui, -apple-system, sans-serif;
  --font-serif: 'Noto Sans SC', 'Georgia', serif;
  --font-mono: 'SF Mono', 'Monaco', 'Menlo', monospace;
  
  /* 间距系统（8px基准）*/
  --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;
  
  /* 排版比例 */
  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 1.875rem;
  --text-4xl: 2.25rem;
  --text-5xl: 3rem;
  --text-6xl: 3.75rem;
  
  /* 行高 */
  --leading-none: 1;
  --leading-tight: 1.25;
  --leading-normal: 1.5;
  --leading-relaxed: 1.625;
  --leading-loose: 2;
  
  /* 字重 */
  --font-light: 300;
  --font-normal: 400;
  --font-medium: 500;
  --font-semibold: 600;
  --font-bold: 700;
  
  /* 圆角 */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-2xl: 24px;
  --radius-full: 9999px;
  
  /* 阴影 */
  --shadow-xs: 0 1px 2px rgba(0,0,0,0.05);
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.1), 0 1px 2px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.07), 0 2px 4px rgba(0,0,0,0.06);
  --shadow-lg: 0 10px 15px rgba(0,0,0,0.1), 0 4px 6px rgba(0,0,0,0.05);
  --shadow-xl: 0 20px 25px rgba(0,0,0,0.1), 0 10px 10px rgba(0,0,0,0.04);
  --shadow-2xl: 0 25px 50px rgba(0,0,0,0.25);
  
  /* 过渡动画 */
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
  --transition-slow: 350ms ease;
  
  /* 断点 */
  --breakpoint-sm: 640px;
  --breakpoint-md: 768px;
  --breakpoint-lg: 1024px;
  --breakpoint-xl: 1280px;
  --breakpoint-2xl: 1536px;
}

/* ==========================================
   2. 亮色主题（默认）
   ========================================== */

:root, [data-theme="light"] {
  --bg-primary: #ffffff;
  --bg-secondary: #f8f9fa;
  --bg-tertiary: #e9ecef;
  --bg-overlay: rgba(0, 0, 0, 0.5);
  
  --text-primary: #1a1a1a;
  --text-secondary: #4a4a4a;
  --text-tertiary: #6c757d;
  --text-placeholder: #adb5bd;
  --text-inverse: #ffffff;
  
  --color-brand-primary: #E53935;
  --color-brand-primary-hover: #c62828;
  --color-brand-primary-light: #ffcdd2;
  --color-brand-secondary: #FF8F00;
  --color-brand-secondary-hover: #e65100;
  --color-brand-accent: #1E88E5;
  --color-brand-accent-hover: #1565c0;
  
  --color-success: #28a745;
  --color-success-light: #d4edda;
  --color-warning: #ffc107;
  --color-warning-light: #fff3cd;
  --color-danger: #dc3545;
  --color-danger-light: #f8d7da;
  --color-info: #17a2b8;
  --color-info-light: #d1ecf1;
  
  --border-primary: #dee2e6;
  --border-secondary: #ced4da;
  --border-focus: var(--color-brand-primary);
  
  --nav-bg: rgba(255, 255, 255, 0.95);
  --nav-shadow: var(--shadow-sm);
}

/* ==========================================
   3. 暗色主题
   ========================================== */

[data-theme="dark"] {
  --bg-primary: #1a1a1a;
  --bg-secondary: #2d2d2d;
  --bg-tertiary: #3d3d3d;
  --bg-overlay: rgba(0, 0, 0, 0.8);
  
  --text-primary: #ffffff;
  --text-secondary: #e0e0e0;
  --text-tertiary: #adb5bd;
  --text-placeholder: #6c757d;
  --text-inverse: #1a1a1a;
  
  --color-brand-primary: #E53935;
  --color-brand-primary-hover: #ef5350;
  --color-brand-primary-light: #4a1a1a;
  --color-brand-secondary: #FF8F00;
  --color-brand-secondary-hover: #ffa726;
  --color-brand-accent: #1E88E5;
  --color-brand-accent-hover: #42a5f5;
  
  --color-success-light: #1a3a1a;
  --color-warning-light: #3a2e1a;
  --color-danger-light: #3a1a1a;
  --color-info-light: #1a2e3a;
  
  --border-primary: #404040;
  --border-secondary: #4a4a4a;
  
  --nav-bg: rgba(26, 26, 26, 0.95);
  --nav-shadow: 0 1px 3px rgba(0,0,0,0.3);
}

/* ==========================================
   4. 系统主题（跟随系统偏好）
   ========================================== */

@media (prefers-color-scheme: dark) {
  :root:not([data-theme]) {
    --bg-primary: #1a1a1a;
    --bg-secondary: #2d2d2d;
    --bg-tertiary: #3d3d3d;
    --bg-overlay: rgba(0, 0, 0, 0.8);
    
    --text-primary: #ffffff;
    --text-secondary: #e0e0e0;
    --text-tertiary: #adb5bd;
    --text-placeholder: #6c757d;
    --text-inverse: #1a1a1a;
    
    --color-brand-primary: #E53935;
    --color-brand-primary-hover: #ef5350;
    --color-brand-primary-light: #4a1a1a;
    --color-brand-secondary: #FF8F00;
    --color-brand-secondary-hover: #ffa726;
    --color-brand-accent: #1E88E5;
    --color-brand-accent-hover: #42a5f5;
    
    --color-success-light: #1a3a1a;
    --color-warning-light: #3a2e1a;
    --color-danger-light: #3a1a1a;
    --color-info-light: #1a2e3a;
    
    --border-primary: #404040;
    --border-secondary: #4a4a4a;
    
    --nav-bg: rgba(26, 26, 26, 0.95);
    --nav-shadow: 0 1px 3px rgba(0,0,0,0.3);
  }
}

/* ==========================================
   5. 基础重置与全局样式
   ========================================== */

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: var(--leading-normal);
  color: var(--text-primary);
  background-color: var(--bg-primary);
  transition: background-color var(--transition-normal),
              color var(--transition-normal);
  min-height: 100vh;
}

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

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

a:hover {
  color: var(--color-brand-primary-hover);
  text-decoration: underline;
}

/* 屏幕阅读器专用类 */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border-width: 0;
}

/* ==========================================
   6. 组件库（BEM规范）
   ========================================== */

/* --- 6.1 卡片组件 --- */

.card {
  background: var(--bg-primary);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  transition: all var(--transition-normal);
  height: 100%;
  display: flex;
  flex-direction: column;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.card--featured {
  border-color: var(--color-brand-primary);
  border-width: 2px;
}

.card--interactive {
  cursor: pointer;
}

.card--interactive:hover {
  text-decoration: none;
}

.card__image {
  width: 100%;
  aspect-ratio: 16 / 9;
  object-fit: cover;
  border-radius: var(--radius-md);
  margin-bottom: var(--space-4);
}

.card__title {
  font-size: var(--text-xl);
  font-weight: var(--font-semibold);
  color: var(--text-primary);
  margin-bottom: var(--space-2);
  line-height: var(--leading-tight);
}

.card__description {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: var(--leading-relaxed);
  flex-grow: 1;
  margin-bottom: var(--space-4);
}

.card__footer {
  margin-top: auto;
  padding-top: var(--space-4);
  border-top: 1px solid var(--border-primary);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
}

/* --- 6.2 按钮组件 --- */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-3) var(--space-6);
  font-size: var(--text-base);
  font-weight: var(--font-medium);
  line-height: 1;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
  min-height: 44px;
  gap: var(--space-2);
  user-select: none;
  white-space: nowrap;
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  text-decoration: none;
}

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

.btn:focus-visible {
  outline: 3px solid var(--color-brand-primary);
  outline-offset: 2px;
}

.btn--primary {
  background: var(--color-brand-primary);
  color: var(--text-inverse);
  border-color: var(--color-brand-primary);
}

.btn--primary:hover {
  background: var(--color-brand-primary-hover);
  border-color: var(--color-brand-primary-hover);
  color: var(--text-inverse);
}

.btn--secondary {
  background: var(--color-brand-primary);
  color: var(--text-inverse);
  border-color: var(--color-brand-primary);
}

.btn--secondary:hover {
  background: var(--color-brand-primary-hover);
  border-color: var(--color-brand-primary-hover);
  color: var(--text-inverse);
}

.btn--secondary svg {
  transition: transform var(--transition-fast);
}

.btn--secondary:hover svg {
  transform: translateX(3px);
}

.btn--outline {
  background: transparent;
  color: var(--text-primary);
  border-color: var(--border-secondary);
}

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

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

.btn--ghost:hover {
  background: var(--bg-secondary);
  color: var(--text-primary);
}

.btn--small {
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-sm);
  min-height: 36px;
}

.btn--large {
  padding: var(--space-4) var(--space-8);
  font-size: var(--text-lg);
  min-height: 52px;
}

.btn--full {
  width: 100%;
}

.btn:disabled,
.btn--disabled {
  opacity: 0.5;
  cursor: not-allowed;
  pointer-events: none;
}

/* --- 6.3 导航组件 --- */

.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: #1a1a1a;
  border-bottom: 1px solid #333333;
  transition: box-shadow var(--transition-normal);
}

.navbar.scrolled {
  background: rgba(26, 26, 26, 0.98);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  box-shadow: 0 1px 3px rgba(0,0,0,0.3);
}

.navbar__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-4) var(--space-6);
  max-width: 1200px;
  margin: 0 auto;
  gap: var(--space-4);
}

.navbar__logo {
  font-size: var(--text-xl);
  font-weight: var(--font-bold);
  color: var(--color-brand-primary);
  text-decoration: none;
  white-space: nowrap;
  display: flex;
  align-items: center;
}

/* Logo 图片尺寸限制 - 防止图片过大 */
.navbar__logo img {
  height: 32px;
  width: auto;
  max-width: 140px;
  object-fit: contain;
  display: block;
}

.navbar__logo:hover {
  text-decoration: none;
  color: var(--color-brand-primary-hover);
}

.navbar__links {
  display: flex;
  align-items: center;
  gap: var(--space-6);
  list-style: none;
}

.navbar__link {
  color: #e0e0e0;
  font-size: var(--text-sm);
  font-weight: var(--font-medium);
  text-decoration: none;
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

.navbar__link:hover {
  color: #ffffff;
  background: rgba(255, 255, 255, 0.1);
  text-decoration: none;
}

.navbar__link--active {
  color: #E53935;
  font-weight: var(--font-semibold);
}

[data-theme="dark"] .navbar__link {
  color: #e0e0e0;
}

[data-theme="dark"] .navbar__link:hover {
  color: #ffffff;
  background: rgba(255, 255, 255, 0.1);
}

[data-theme="dark"] .navbar__link--active {
  color: #E53935;
}

/* --- 6.4 主题切换器组件 --- */

.theme-toggle {
  display: inline-flex;
  align-items: center;
  background: var(--bg-secondary);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-full);
  padding: var(--space-1);
  gap: var(--space-1);
}

.theme-toggle__option {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border: none;
  background: transparent;
  color: var(--text-tertiary);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.theme-toggle__option:hover {
  color: var(--text-primary);
  background: var(--bg-tertiary);
}

.theme-toggle__option[aria-checked="true"] {
  color: var(--text-inverse);
  background: var(--color-brand-primary);
}

.theme-toggle__option svg {
  width: 16px;
  height: 16px;
}

/* --- 6.5 网格系统 --- */

.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--space-4);
}

.grid {
  display: grid;
  gap: var(--space-6);
}

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

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

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

/* --- 6.6 表单组件 --- */

.form-group {
  margin-bottom: var(--space-4);
}

.form-label {
  display: block;
  font-size: var(--text-sm);
  font-weight: var(--font-medium);
  color: var(--text-primary);
  margin-bottom: var(--space-2);
}

.form-input,
.form-select,
.form-textarea {
  width: 100%;
  padding: var(--space-3) var(--space-4);
  font-size: var(--text-base);
  font-family: var(--font-sans);
  color: var(--text-primary);
  background: var(--bg-primary);
  border: 1px solid var(--border-secondary);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  min-height: 44px;
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
  outline: none;
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px var(--color-brand-primary-light);
}

.form-input::placeholder,
.form-textarea::placeholder {
  color: var(--text-placeholder);
}

.form-textarea {
  min-height: 120px;
  resize: vertical;
}

/* --- 6.7 页脚组件 --- */

.footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-primary);
  padding: var(--space-16) 0 var(--space-8);
  margin-top: auto;
}

.footer__inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-6);
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-8);
}

.footer__title {
  font-size: var(--text-base);
  font-weight: var(--font-semibold);
  color: var(--text-primary);
  margin-bottom: var(--space-4);
}

.footer__links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.footer__link {
  color: var(--text-secondary);
  font-size: var(--text-sm);
  text-decoration: none;
  transition: color var(--transition-fast);
}

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

.footer__bottom {
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--space-6) var(--space-6) 0;
  border-top: 1px solid var(--border-primary);
  margin-top: var(--space-8);
  text-align: center;
  color: var(--text-tertiary);
  font-size: var(--text-sm);
}

/* ==========================================
   7. 响应式断点系统（移动优先）
   ========================================== */

/* 小屏（≥ 640px）*/
@media (min-width: 640px) {
  .container {
    padding: var(--space-6);
  }
  
  .grid--responsive {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* 平板（≥ 768px）*/
@media (min-width: 768px) {
  .container {
    max-width: 720px;
  }
}

/* 桌面（≥ 1024px）*/
@media (min-width: 1024px) {
  .container {
    max-width: 960px;
  }
  
  .grid--responsive {
    grid-template-columns: repeat(3, 1fr);
  }
}

/* 大屏（≥ 1280px）*/
@media (min-width: 1280px) {
  .container {
    max-width: 1200px;
  }
  
  .grid--responsive {
    grid-template-columns: repeat(4, 1fr);
  }
}

/* ==========================================
   8. 可访问性增强
   ========================================== */

/* 焦点样式 */
:focus {
  outline: 3px solid var(--color-brand-primary);
  outline-offset: 2px;
}

:focus:not(:focus-visible) {
  outline: none;
}

:focus-visible {
  outline: 3px solid var(--color-brand-primary);
  outline-offset: 2px;
}

/* 跳过导航链接 */
.skip-link {
  position: absolute;
  top: -40px;
  left: var(--space-4);
  background: var(--color-brand-primary);
  color: white;
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-md);
  text-decoration: none;
  z-index: 10000;
  transition: top var(--transition-normal);
}

.skip-link:focus {
  top: var(--space-4);
}

/* 高对比度模式支持 */
@media (prefers-contrast: high) {
  :root {
    --border-primary: #000000;
    --text-primary: #000000;
    --text-secondary: #333333;
  }
  
  [data-theme="dark"] {
    --border-primary: #ffffff;
    --text-primary: #ffffff;
    --text-secondary: #cccccc;
  }
}

/* 减少动画 */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* 触摸优化 */
@media (pointer: coarse) {
  .btn,
  .navbar__link,
  .card,
  .form-input,
  .form-select,
  .form-textarea {
    min-height: 44px;
    min-width: 44px;
  }
}

@media (hover: none) {
  .card:hover {
    transform: none;
    box-shadow: none;
  }
  
  .btn:hover {
    transform: none;
  }
}