/* ============================================
   全局样式 - 模仿 labpai.com 设计风格
   ============================================ */

/* CSS 变量 - 配色方案 */
:root {
  --color-bg: #ffffff;
  --color-bg-secondary: #f8f9fa;
  --color-text: #1a1a1a;
  --color-text-secondary: #4a4a4a;
  --color-accent: #2563eb;
  --color-accent-hover: #1d4ed8;
  --color-border: #e5e7eb;
  --color-link: #2563eb;
  --color-link-hover: #1d4ed8;
  
  --font-primary: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: "SF Mono", Monaco, "Cascadia Code", "Roboto Mono", Consolas, monospace;
  
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 2rem;
  --spacing-lg: 3rem;
  --spacing-xl: 4rem;
  --spacing-2xl: 6rem;
  
  --max-width: 1200px;
  --max-width-content: 900px;
  
  --transition: all 0.3s ease;
}

/* 重置样式 */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

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

body {
  font-family: var(--font-primary);
  color: var(--color-text);
  background-color: var(--color-bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ============================================
   头部导航栏样式
   ============================================ */

.site-header {
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 1000;
  backdrop-filter: blur(10px);
  background-color: rgba(255, 255, 255, 0.95);
}

.header-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--spacing-sm) var(--spacing-md);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo-link {
  text-decoration: none;
  color: var(--color-text);
  font-weight: 600;
  font-size: 1.25rem;
  transition: var(--transition);
}

.logo-link:hover {
  color: var(--color-accent);
}

.logo-text {
  letter-spacing: -0.02em;
}

.main-nav {
  display: flex;
  align-items: center;
}

.nav-list {
  display: flex;
  list-style: none;
  gap: var(--spacing-md);
  align-items: center;
}

.nav-item {
  margin: 0;
}

.nav-link {
  text-decoration: none;
  color: var(--color-text);
  font-size: 0.95rem;
  font-weight: 400;
  padding: var(--spacing-xs) 0;
  position: relative;
  transition: var(--transition);
  letter-spacing: 0.01em;
}

.nav-link:hover {
  color: var(--color-accent);
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--color-accent);
  transition: width 0.3s ease;
}

.nav-link:hover::after {
  width: 100%;
}

.nav-link.active {
  color: var(--color-accent);
  font-weight: 500;
}

.nav-link.active::after {
  width: 100%;
}

/* 移动端菜单切换按钮 */
.mobile-menu-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--spacing-xs);
  z-index: 1001;
}

.mobile-menu-toggle span {
  width: 24px;
  height: 2px;
  background-color: var(--color-text);
  transition: var(--transition);
}

/* ============================================
   主内容区域样式
   ============================================ */

.main-content {
  min-height: calc(100vh - 200px);
  padding: var(--spacing-xl) var(--spacing-md);
}

.content-container {
  max-width: var(--max-width-content);
  margin: 0 auto;
}

/* 页面标题 */
.page-title {
  font-size: 2.5rem;
  font-weight: 600;
  margin-bottom: var(--spacing-md);
  letter-spacing: -0.03em;
  line-height: 1.2;
  color: var(--color-text);
}

.page-subtitle {
  font-size: 1.25rem;
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-xl);
  font-weight: 300;
  line-height: 1.6;
}

/* 段落样式 */
.content-section {
  margin-bottom: var(--spacing-xl);
}

.content-section p {
  margin-bottom: var(--spacing-md);
  color: var(--color-text);
  line-height: 1.8;
  font-size: 1rem;
}

.content-section h2 {
  font-size: 1.75rem;
  font-weight: 600;
  margin-top: var(--spacing-xl);
  margin-bottom: var(--spacing-md);
  color: var(--color-text);
  letter-spacing: -0.02em;
}

.content-section h3 {
  font-size: 1.5rem;
  font-weight: 600;
  margin-top: var(--spacing-lg);
  margin-bottom: var(--spacing-sm);
  color: var(--color-text);
  letter-spacing: -0.01em;
}

/* 链接样式 */
a {
  color: var(--color-link);
  text-decoration: none;
  transition: var(--transition);
}

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

/* ============================================
   卡片样式
   ============================================ */

.card {
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 8px;
  padding: var(--spacing-lg);
  margin-bottom: var(--spacing-md);
  transition: var(--transition);
}

.card:hover {
  border-color: var(--color-accent);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.08);
}

.card-title {
  font-size: 1.5rem;
  font-weight: 600;
  margin-bottom: var(--spacing-sm);
  color: var(--color-text);
}

.card-content {
  color: var(--color-text-secondary);
  line-height: 1.7;
}

/* 项目网格 */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: var(--spacing-md);
  margin-top: var(--spacing-lg);
}

.project-card {
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 8px;
  padding: var(--spacing-lg);
  transition: var(--transition);
}

.project-card:hover {
  border-color: var(--color-accent);
  transform: translateY(-2px);
  box-shadow: 0 8px 16px rgba(37, 99, 235, 0.1);
}

.project-title {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: var(--spacing-sm);
  color: var(--color-text);
}

.project-description {
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: var(--spacing-sm);
}

.project-link {
  color: var(--color-accent);
  font-weight: 500;
  font-size: 0.9rem;
}

/* ============================================
   联系表单样式
   ============================================ */

.contact-form {
  max-width: 600px;
  margin-top: var(--spacing-lg);
}

.form-group {
  margin-bottom: var(--spacing-md);
}

.form-label {
  display: block;
  margin-bottom: var(--spacing-xs);
  font-weight: 500;
  color: var(--color-text);
  font-size: 0.95rem;
}

.form-input,
.form-textarea {
  width: 100%;
  padding: var(--spacing-sm);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  font-family: var(--font-primary);
  font-size: 1rem;
  color: var(--color-text);
  background-color: var(--color-bg);
  transition: var(--transition);
}

.form-input:focus,
.form-textarea:focus {
  outline: none;
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.form-textarea {
  min-height: 150px;
  resize: vertical;
}

.form-button {
  background-color: var(--color-accent);
  color: white;
  border: none;
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: 4px;
  font-size: 1rem;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
}

.form-button:hover {
  background-color: var(--color-accent-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 8px rgba(37, 99, 235, 0.2);
}

.contact-info {
  margin-top: var(--spacing-xl);
}

.contact-info-item {
  margin-bottom: var(--spacing-sm);
  color: var(--color-text-secondary);
}

.contact-info-item strong {
  color: var(--color-text);
  font-weight: 600;
}

/* ============================================
   页脚样式
   ============================================ */

.site-footer {
  background-color: var(--color-bg-secondary);
  border-top: 1px solid var(--color-border);
  padding: var(--spacing-lg) var(--spacing-md);
  margin-top: var(--spacing-2xl);
}

.footer-container {
  max-width: var(--max-width);
  margin: 0 auto;
}

.footer-content {
  text-align: center;
}

.footer-text {
  color: var(--color-text-secondary);
  font-size: 0.9rem;
  margin-bottom: var(--spacing-xs);
}

/* ============================================
   响应式设计
   ============================================ */

@media (max-width: 768px) {
  :root {
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
  }
  
  .header-container {
    padding: var(--spacing-sm);
  }
  
  .mobile-menu-toggle {
    display: flex;
  }
  
  .nav-list {
    position: fixed;
    top: 60px;
    left: 0;
    right: 0;
    background-color: var(--color-bg);
    flex-direction: column;
    padding: var(--spacing-md);
    border-bottom: 1px solid var(--color-border);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    transform: translateY(-100%);
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    gap: var(--spacing-sm);
  }
  
  .nav-list.active {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }
  
  .nav-item {
    width: 100%;
  }
  
  .nav-link {
    display: block;
    padding: var(--spacing-sm);
    width: 100%;
  }
  
  .page-title {
    font-size: 2rem;
  }
  
  .page-subtitle {
    font-size: 1.1rem;
  }
  
  .main-content {
    padding: var(--spacing-lg) var(--spacing-sm);
  }
  
  .projects-grid {
    grid-template-columns: 1fr;
  }
  
  .content-section h2 {
    font-size: 1.5rem;
  }
  
  .content-section h3 {
    font-size: 1.25rem;
  }
}

@media (max-width: 480px) {
  .page-title {
    font-size: 1.75rem;
  }
  
  .logo-text {
    font-size: 1.1rem;
  }
  
  .card {
    padding: var(--spacing-md);
  }
}

/* ============================================
   工具类
   ============================================ */

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

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

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

.section-divider {
  height: 1px;
  background-color: var(--color-border);
  margin: var(--spacing-xl) 0;
  border: none;
}