/* 复古球鞋 - 案例展示风格 CSS */
/* 变量定义 */
:root {
  --accent-color: #00bcd4;
  --accent-dark: #0097a7;
  --text-primary: #333;
  --text-secondary: #666;
  --text-light: #999;
  --bg-primary: #fff;
  --bg-secondary: #f5f5f5;
  --bg-dark: #1a1a1a;
  --border-color: #e0e0e0;
  --shadow: 0 2px 8px rgba(0,0,0,0.1);
  --shadow-hover: 0 4px 16px rgba(0,0,0,0.15);
  --radius: 8px;
  --radius-lg: 12px;
  --max-width: 1200px;
  --header-height: 64px;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  line-height: 1.6;
  color: var(--text-primary);
  background: var(--bg-primary);
}

a {
  text-decoration: none;
  color: inherit;
}

ul {
  list-style: none;
}

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

/* 容器 */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

/* Header */
.header {
  height: var(--header-height);
  background: var(--bg-primary);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 100;
}

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

.logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--accent-color);
}

.nav {
  display: flex;
  gap: 32px;
}

.nav a {
  font-size: 0.95rem;
  color: var(--text-secondary);
  transition: color 0.3s;
}

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

/* Breadcrumb */
.breadcrumb {
  background: var(--bg-secondary);
  padding: 12px 0;
  font-size: 0.875rem;
  color: var(--text-light);
}

.breadcrumb a {
  color: var(--text-secondary);
}

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

.breadcrumb span {
  margin: 0 8px;
}

/* Split Screen Layout */
.split-section {
  padding: 60px 0;
}

.split-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 40px;
  align-items: stretch;
}

.split-panel {
  background: var(--bg-secondary);
  border-radius: var(--radius-lg);
  padding: 48px;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.split-panel h2 {
  font-size: 2rem;
  margin-bottom: 16px;
  color: var(--text-primary);
}

.split-panel p {
  color: var(--text-secondary);
  margin-bottom: 24px;
  line-height: 1.8;
}

.split-panel .btn {
  align-self: flex-start;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 28px;
  border-radius: var(--radius);
  font-size: 0.95rem;
  font-weight: 500;
  transition: all 0.3s;
  cursor: pointer;
  border: none;
}

.btn-primary {
  background: var(--accent-color);
  color: #fff;
}

.btn-primary:hover {
  background: var(--accent-dark);
  transform: translateY(-2px);
  box-shadow: var(--shadow-hover);
}

.btn-outline {
  background: transparent;
  color: var(--accent-color);
  border: 2px solid var(--accent-color);
}

.btn-outline:hover {
  background: var(--accent-color);
  color: #fff;
}

/* Three Column Section */
.three-col-section {
  padding: 60px 0;
  background: var(--bg-secondary);
}

.section-title {
  font-size: 1.5rem;
  margin-bottom: 32px;
  text-align: center;
  color: var(--text-primary);
}

.three-col-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.col-panel {
  background: var(--bg-primary);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
}

.col-panel h3 {
  font-size: 1.1rem;
  margin-bottom: 16px;
  color: var(--accent-color);
  padding-bottom: 12px;
  border-bottom: 2px solid var(--border-color);
}

.col-panel ul li {
  padding: 10px 0;
  border-bottom: 1px solid var(--border-color);
  font-size: 0.95rem;
}

.col-panel ul li:last-child {
  border-bottom: none;
}

.col-panel ul li a {
  color: var(--text-secondary);
  display: block;
  transition: color 0.3s;
}

.col-panel ul li a:hover {
  color: var(--accent-color);
}

/* Category Grid */
.category-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 40px;
}

.category-block {
  background: var(--bg-secondary);
  border-radius: var(--radius-lg);
  padding: 32px;
}

.category-block h3 {
  font-size: 1.25rem;
  margin-bottom: 20px;
  color: var(--text-primary);
}

.category-block ul {
  margin-bottom: 20px;
}

.category-block ul li {
  padding: 8px 0;
  color: var(--text-secondary);
  font-size: 0.95rem;
}

.category-block ul li::before {
  content: "•";
  color: var(--accent-color);
  margin-right: 8px;
}

/* Article Layout */
.article-section {
  padding: 60px 0;
}

.article-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 40px;
}

.article-panel {
  background: var(--bg-secondary);
  border-radius: var(--radius-lg);
  padding: 40px;
}

.article-panel h1 {
  font-size: 1.75rem;
  margin-bottom: 20px;
  color: var(--text-primary);
}

.article-panel h2 {
  font-size: 1.25rem;
  margin: 24px 0 12px;
  color: var(--text-primary);
}

.article-panel p {
  color: var(--text-secondary);
  line-height: 1.8;
  margin-bottom: 16px;
}

.article-meta {
  display: flex;
  gap: 16px;
  font-size: 0.875rem;
  color: var(--text-light);
  margin-bottom: 20px;
}

/* Related Section */
.related-section {
  padding: 40px 0;
  background: var(--bg-secondary);
}

.related-list {
  display: flex;
  justify-content: center;
  gap: 32px;
  flex-wrap: wrap;
}

.related-list a {
  color: var(--text-secondary);
  font-size: 0.95rem;
}

.related-list a:hover {
  color: var(--accent-color);
}

/* Two Column Section */
.two-col-section {
  padding: 40px 0;
}

.two-col-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

/* 404 Page */
.error-section {
  min-height: calc(100vh - var(--header-height) - 200px);
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 60px 0;
}

.error-content h1 {
  font-size: 6rem;
  color: var(--accent-color);
  line-height: 1;
  margin-bottom: 16px;
}

.error-content h2 {
  font-size: 1.5rem;
  color: var(--text-primary);
  margin-bottom: 16px;
}

.error-content p {
  color: var(--text-secondary);
  margin-bottom: 32px;
}

/* Footer */
.footer {
  background: var(--bg-dark);
  color: #fff;
  padding: 48px 0 24px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 32px;
}

.footer-brand .logo {
  margin-bottom: 16px;
  display: inline-block;
}

.footer-brand p {
  color: var(--text-light);
  font-size: 0.9rem;
  line-height: 1.7;
}

.footer-col h4 {
  font-size: 1rem;
  margin-bottom: 16px;
  color: #fff;
}

.footer-col ul li {
  margin-bottom: 10px;
}

.footer-col ul li a {
  color: var(--text-light);
  font-size: 0.9rem;
  transition: color 0.3s;
}

.footer-col ul li a:hover {
  color: var(--accent-color);
}

.footer-bottom {
  border-top: 1px solid #333;
  padding-top: 24px;
  text-align: center;
  color: var(--text-light);
  font-size: 0.875rem;
}

/* Responsive Design */
@media (max-width: 992px) {
  .split-grid,
  .category-grid,
  .article-grid {
    grid-template-columns: 1fr;
    gap: 24px;
  }

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

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

  .split-panel {
    padding: 32px;
  }
}

@media (max-width: 768px) {
  .nav {
    display: none;
  }

  .three-col-grid,
  .two-col-grid {
    grid-template-columns: 1fr;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .split-panel h2 {
    font-size: 1.5rem;
  }

  .error-content h1 {
    font-size: 4rem;
  }

  .related-list {
    flex-direction: column;
    align-items: center;
    gap: 16px;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 16px;
  }

  .split-panel,
  .category-block,
  .article-panel {
    padding: 24px;
  }

  .btn {
    width: 100%;
  }
}