/* ============================================
   全局样式 - CSS 变量、重置样式、主题系统
   ============================================ */

/* CSS 变量定义 - 浅色模式（极致黑白） */
:root {
  /* 主色调 - 纯黑 */
  --color-primary: #000000;
  --color-primary-hover: #1a1a1a;
  --color-primary-light: #333333;
  
  /* 辅助色 - 灰度 */
  --color-secondary: #666666;
  --color-success: #000000;
  --color-warning: #000000;
  --color-error: #000000;
  
  /* 背景色 - 纯白到浅灰 */
  --color-bg: #FFFFFF;
  --color-bg-secondary: #FAFAFA;
  --color-bg-tertiary: #F5F5F5;
  --color-bg-hover: #F0F0F0;
  
  /* 边框色 - 极细灰度 */
  --color-border: #E0E0E0;
  --color-border-hover: #C0C0C0;
  --color-border-strong: #999999;
  
  /* 文字颜色 - 黑白灰度 */
  --color-text: #000000;
  --color-text-secondary: #666666;
  --color-text-tertiary: #999999;
  --color-text-disabled: #CCCCCC;
  
  /* 阴影 - 更硬朗的阴影 */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow-md: 0 2px 4px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 4px 8px rgba(0, 0, 0, 0.12);
  --shadow-xl: 0 8px 16px rgba(0, 0, 0, 0.16);
  --shadow-2xl: 0 16px 32px rgba(0, 0, 0, 0.24);
  
  /* 间距系统 */
  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
  --spacing-xl: 32px;
  --spacing-2xl: 48px;
  --spacing-3xl: 64px;
  --spacing-4xl: 96px;
  
  /* 圆角 - 科技直角风格 */
  --radius-sm: 0px;
  --radius-md: 0px;
  --radius-lg: 0px;
  --radius-xl: 0px;
  --radius-2xl: 0px;
  --radius-full: 0px;
  
  /* 过渡 */
  --transition-fast: 100ms;
  --transition-base: 150ms;
  --transition-slow: 300ms;
  --ease-smooth: cubic-bezier(0.4, 0, 0.2, 1);
  --ease-bounce: cubic-bezier(0.68, -0.55, 0.27, 1.55);
  --ease-swift: cubic-bezier(0.55, 0, 0.1, 1);
  
  /* 字体 */
  --font-family: Inter, -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  
  /* 断点 */
  --breakpoint-mobile: 768px;
  --breakpoint-tablet: 1024px;
  --breakpoint-desktop: 1440px;
}

/* 暗色模式变量（极致黑白反转） */
[data-theme="dark"] {
  /* 主色调 - 纯白 */
  --color-primary: #FFFFFF;
  --color-primary-hover: #E0E0E0;
  --color-primary-light: #CCCCCC;
  
  /* 辅助色 - 灰度 */
  --color-secondary: #999999;
  --color-success: #FFFFFF;
  --color-warning: #FFFFFF;
  --color-error: #FFFFFF;
  
  /* 背景色 - 纯黑到深灰 */
  --color-bg: #000000;
  --color-bg-secondary: #0A0A0A;
  --color-bg-tertiary: #1A1A1A;
  --color-bg-hover: #252525;
  
  /* 边框色 - 深灰 */
  --color-border: #2A2A2A;
  --color-border-hover: #3A3A3A;
  --color-border-strong: #4A4A4A;
  
  /* 文字颜色 - 白色灰度 */
  --color-text: #FFFFFF;
  --color-text-secondary: #999999;
  --color-text-tertiary: #666666;
  --color-text-disabled: #3A3A3A;
  
  /* 阴影 - 暗色下用发光效果 */
  --shadow-sm: 0 0 0 1px rgba(255, 255, 255, 0.06);
  --shadow-md: 0 0 0 1px rgba(255, 255, 255, 0.08);
  --shadow-lg: 0 0 0 1px rgba(255, 255, 255, 0.1);
  --shadow-xl: 0 0 0 1px rgba(255, 255, 255, 0.12);
  --shadow-2xl: 0 0 0 1px rgba(255, 255, 255, 0.16);
}

/* ============================================
   CSS Reset
   ============================================ */

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

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

body {
  font-family: var(--font-family);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  transition: background-color var(--transition-slow) var(--ease-smooth),
              color var(--transition-slow) var(--ease-smooth);
}

/* 禁止页面滚动（弹窗打开时使用） */
body.no-scroll {
  overflow: hidden;
}

/* ============================================
   排版
   ============================================ */

h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.2;
  color: var(--color-text);
}

h1 {
  font-size: 3.5rem;
  letter-spacing: -0.02em;
}

h2 {
  font-size: 2.5rem;
  letter-spacing: -0.01em;
}

h3 {
  font-size: 2rem;
}

h4 {
  font-size: 1.5rem;
}

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

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition-base) var(--ease-smooth);
}

a:hover {
  color: var(--color-primary-hover);
}

a:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 4px;
  border-radius: var(--radius-sm);
}

/* ============================================
   布局工具类
   ============================================ */

.container {
  width: 100%;
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

.section {
  padding: var(--spacing-4xl) 0;
}

.section-sm {
  padding: var(--spacing-2xl) 0;
}

.flex {
  display: flex;
}

.flex-col {
  flex-direction: column;
}

.items-center {
  align-items: center;
}

.justify-center {
  justify-content: center;
}

.justify-between {
  justify-content: space-between;
}

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

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

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

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

.grid {
  display: grid;
}

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

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

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

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

/* ============================================
   响应式工具类
   ============================================ */

@media (max-width: 768px) {
  h1 {
    font-size: 2.5rem;
  }
  
  h2 {
    font-size: 2rem;
  }
  
  h3 {
    font-size: 1.5rem;
  }
  
  .container {
    padding: 0 var(--spacing-md);
  }
  
  .section {
    padding: var(--spacing-3xl) 0;
  }
  
  .grid-cols-2,
  .grid-cols-3,
  .grid-cols-4 {
    grid-template-columns: 1fr;
  }
}

@media (min-width: 769px) and (max-width: 1024px) {
  .grid-cols-3,
  .grid-cols-4 {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1440px) {
  .container {
    max-width: 1440px;
  }
}

/* ============================================
   可访问性
   ============================================ */

/* 跳转到主内容链接（屏幕阅读器） */
.skip-to-main {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--color-primary);
  color: white;
  padding: var(--spacing-sm) var(--spacing-md);
  text-decoration: none;
  border-radius: var(--radius-md);
  z-index: 100;
}

.skip-to-main:focus {
  top: 0;
}

/* 焦点指示器 */
button:focus-visible,
input:focus-visible,
textarea:focus-visible,
select:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* 隐藏元素但保持可访问性 */
.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;
}

/* ============================================
   装饰性背景
   ============================================ */

.bg-grid {
  background-image: linear-gradient(var(--color-border) 1px, transparent 1px),
                    linear-gradient(90deg, var(--color-border) 1px, transparent 1px);
  background-size: 32px 32px;
  background-position: -1px -1px;
}

.bg-gradient-radial {
  background: radial-gradient(
    circle at 50% 50%,
    rgba(0, 0, 0, 0.02) 0%,
    rgba(0, 0, 0, 0.01) 40%,
    transparent 70%
  );
}

/* 暗色模式下调整装饰 */
[data-theme="dark"] .bg-gradient-radial {
  background: radial-gradient(
    circle at 50% 50%,
    rgba(255, 255, 255, 0.03) 0%,
    rgba(255, 255, 255, 0.01) 40%,
    transparent 70%
  );
}

/* 科技感装饰 - 动态网格 */
.tech-grid {
  position: absolute;
  inset: 0;
  background-image: 
    linear-gradient(var(--color-border) 1px, transparent 1px),
    linear-gradient(90deg, var(--color-border) 1px, transparent 1px);
  background-size: 100px 100px;
  background-position: -1px -1px;
  opacity: 0.3;
  pointer-events: none;
}

/* 扫描线效果 */
.scan-line {
  position: absolute;
  width: 100%;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--color-text), transparent);
  opacity: 0.1;
  animation: scan 8s linear infinite;
  pointer-events: none;
}

@keyframes scan {
  0% { transform: translateY(-100%); }
  100% { transform: translateY(100vh); }
}

/* 光束效果 */
.light-beam {
  position: absolute;
  width: 1px;
  height: 100%;
  background: linear-gradient(180deg, transparent, var(--color-text), transparent);
  opacity: 0.05;
  pointer-events: none;
}

/* 噪点纹理 */
.noise-texture {
  position: absolute;
  inset: 0;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 400 400' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noiseFilter'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noiseFilter)' opacity='0.05'/%3E%3C/svg%3E");
  opacity: 0.4;
  mix-blend-mode: overlay;
  pointer-events: none;
}