/* ==================== 全局样式 ==================== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  /* 色彩系统 */
  --color-bg-primary: #0a0e27;
  --color-bg-secondary: #151932;
  --color-accent-cyan: #00d9ff;
  --color-accent-purple: #a855f7;
  --color-accent-orange: #ff6b35;
  --color-text-primary: #ffffff;
  --color-text-secondary: #a0aec0;
  --color-text-muted: #718096;

  /* 间距系统 */
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 1.5rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
  --spacing-2xl: 4rem;

  /* 字体系统 */
  --font-family-base:
    "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.5rem;
  --font-size-2xl: 2rem;
  --font-size-3xl: 2.5rem;

  /* 圆角 */
  --radius-sm: 0.5rem;
  --radius-md: 1rem;
  --radius-lg: 1.5rem;

  /* 阴影 */
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.2);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.3);
  --shadow-glow-cyan: 0 0 40px rgba(0, 217, 255, 0.3);
  --shadow-glow-purple: 0 0 40px rgba(168, 85, 247, 0.3);
}

body {
  font-family: var(--font-family-base);
  background: var(--color-bg-primary);
  color: var(--color-text-primary);
  line-height: 1.6;
  overflow-x: hidden;
  min-height: 100vh;
}

/* ==================== 容器布局 ==================== */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--spacing-lg);
  position: relative;
  z-index: 1;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* ==================== 头部样式 ==================== */
.header {
  text-align: center;
  padding: var(--spacing-2xl) 0;
  animation: fadeInDown 0.8s ease-out;
}

.logo h1 {
  font-size: var(--font-size-3xl);
  font-weight: 700;
  background: linear-gradient(
    135deg,
    var(--color-accent-cyan),
    var(--color-accent-purple)
  );
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: var(--spacing-xs);
  letter-spacing: -0.02em;
}

.tagline {
  font-size: var(--font-size-lg);
  color: var(--color-text-secondary);
  font-weight: 300;
}

/* ==================== 主内容区域 ==================== */
.main-content {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-xl) 0;
}

.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: var(--spacing-xl);
  width: 100%;
  animation: fadeInUp 0.8s ease-out 0.2s backwards;
}

/* ==================== 卡片样式 ==================== */
.card {
  background: rgba(21, 25, 50, 0.6);
  backdrop-filter: blur(20px);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: var(--radius-lg);
  padding: var(--spacing-xl);
  position: relative;
  overflow: hidden;
  transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  cursor: pointer;
}

.card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(135deg, transparent, rgba(255, 255, 255, 0.05));
  opacity: 0;
  transition: opacity 0.4s ease;
}

.card:hover {
  transform: translateY(-8px);
  border-color: rgba(255, 255, 255, 0.2);
}

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

.card-marathon:hover {
  box-shadow: var(--shadow-glow-cyan);
}

.card-ai:hover {
  box-shadow: var(--shadow-glow-purple);
}

.card-icon {
  font-size: 3rem;
  margin-bottom: var(--spacing-md);
  display: inline-block;
  animation: float 3s ease-in-out infinite;
}

.card-title {
  font-size: var(--font-size-2xl);
  font-weight: 700;
  margin-bottom: var(--spacing-sm);
  color: var(--color-text-primary);
}

.card-description {
  font-size: var(--font-size-base);
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-lg);
  line-height: 1.7;
}

.card-stats {
  display: flex;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-lg);
  flex-wrap: wrap;
}

.stat-item {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
}

.stat-label {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.stat-value {
  font-size: var(--font-size-base);
  font-weight: 600;
  color: var(--color-text-primary);
}

.card-link {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-xs);
  color: var(--color-accent-cyan);
  text-decoration: none;
  font-weight: 600;
  transition: all 0.3s ease;
  position: relative;
}

.card-ai .card-link {
  color: var(--color-accent-purple);
}

.card-link svg {
  transition: transform 0.3s ease;
}

.card-link:hover svg {
  transform: translateX(4px);
}

/* ==================== 页脚样式 ==================== */
.footer {
  padding: var(--spacing-xl) 0 var(--spacing-lg);
  text-align: center;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  margin-top: auto;
}

.footer-content {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.copyright {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
}

.icp {
  font-size: var(--font-size-sm);
}

.icp a {
  color: var(--color-text-muted);
  text-decoration: none;
  transition: color 0.3s ease;
}

.icp a:hover {
  color: var(--color-accent-cyan);
}

/* ==================== 背景装饰 ==================== */
.bg-decoration {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
  pointer-events: none;
  overflow: hidden;
}

.bg-circle {
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
  opacity: 0.3;
  animation: pulse 8s ease-in-out infinite;
}

.bg-circle-1 {
  width: 500px;
  height: 500px;
  background: var(--color-accent-cyan);
  top: -250px;
  right: -250px;
  animation-delay: 0s;
}

.bg-circle-2 {
  width: 400px;
  height: 400px;
  background: var(--color-accent-purple);
  bottom: -200px;
  left: -200px;
  animation-delay: 2s;
}

.bg-circle-3 {
  width: 300px;
  height: 300px;
  background: var(--color-accent-orange);
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  animation-delay: 4s;
}

/* ==================== 动画 ==================== */
@keyframes fadeInDown {
  from {
    opacity: 0;
    transform: translateY(-30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes float {
  0%,
  100% {
    transform: translateY(0);
  }
  50% {
    transform: translateY(-10px);
  }
}

@keyframes pulse {
  0%,
  100% {
    opacity: 0.3;
    transform: scale(1);
  }
  50% {
    opacity: 0.5;
    transform: scale(1.1);
  }
}

/* ==================== 响应式设计 ==================== */
@media (max-width: 768px) {
  .logo h1 {
    font-size: var(--font-size-2xl);
  }

  .tagline {
    font-size: var(--font-size-base);
  }

  .cards-grid {
    grid-template-columns: 1fr;
    gap: var(--spacing-lg);
  }

  .card {
    padding: var(--spacing-lg);
  }

  .card-title {
    font-size: var(--font-size-xl);
  }

  .bg-circle-1,
  .bg-circle-2,
  .bg-circle-3 {
    width: 300px;
    height: 300px;
  }
}

@media (max-width: 480px) {
  .container {
    padding: var(--spacing-sm);
  }

  .header {
    padding: var(--spacing-lg) 0;
  }

  .card-stats {
    flex-direction: column;
    gap: var(--spacing-sm);
  }
}