/* ===== 全局样式与变量定义 ===== */
:root {
    --font-heading: 'Playfair Display', serif;
    --font-body: 'Lato', sans-serif;
  
    --color-background: #121212;
    --color-surface: #1E1E1E;
    --color-text-primary: #E0E0E0;
    --color-text-secondary: #B0B0B0;
    --color-accent: #3B82F6;
    --color-accent-hover: #60A5FA;
    --color-border: #333333;
  }
  
  /* --- 基础重置与页面设置 --- */
  *, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
  }
  
  body {
    font-family: var(--font-body);
    background-color: var(--color-background);
    color: var(--color-text-primary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
  }
  
  .container {
    max-width: 800px;
    margin: 0 auto;
    padding: 4rem 2rem;
  }
  
  /* ===== 元素样式 ===== */
  h1, h2 {
    font-family: var(--font-heading);
    color: var(--color-text-primary);
    font-weight: 700;
  }
  
  a {
    color: var(--color-accent);
    text-decoration: none;
    transition: color 0.3s ease;
  }
  
  a:hover {
    color: var(--color-accent-hover);
  }
  
  /* ===== 首屏区域 (Hero Section) ===== */
  .hero-section {
    text-align: center;
    margin-bottom: 4rem;
  }
  
  .hero-section h1 {
    font-size: 3rem;
    margin-bottom: 0.5rem;
  }
  
  .hero-section.subtitle {
    font-size: 1.25rem;
    color: var(--color-text-secondary);
    font-weight: 400;
    margin-bottom: 0.25rem;
  }
  
  .hero-section.affiliation {
    font-size: 1rem;
    color: var(--color-text-secondary);
  }
  
  /* ===== 研究卡片 (Research Card) ===== */
  .research-section {
    display: flex;
    flex-direction: column;
    gap: 2.5rem; /* 卡片之间的间距 */
  }
  
  .research-card {
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    padding: 2rem;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
  }
  
  .research-card:hover {
    transform: translateY(-5px); /* 悬停时轻微上浮 */
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.2);
  }
  
  .research-card header {
    margin-bottom: 1rem;
  }
  
  .research-card h2 {
    font-size: 1.75rem;
    margin-bottom: 0.25rem;
  }
  
  .research-card.publication-info {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    font-weight: 700;
  }
  
  .research-card.summary {
    margin-bottom: 1.5rem;
    color: var(--color-text-secondary);
  }
  
  .research-card.summary strong {
    color: var(--color-text-primary);
    font-weight: 700;
  }
  
  .research-card.keywords {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
  }
  
  .research-card.keywords span {
    background-color: rgba(59, 130, 246, 0.1); /* 使用强调色的低透明度版本作为背景 */
    color: var(--color-accent);
    padding: 0.25rem 0.75rem;
    border-radius: 999px; /* 胶囊形状 */
    font-size: 0.8rem;
    font-weight: 700;
  }
  
  .research-card footer {
    display: flex;
    gap: 1.5rem;
    align-items: center;
  }
  
  .icon-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 700;
    color: var(--color-text-secondary);
  }
  
  .icon-link svg {
    stroke: var(--color-text-secondary);
    transition: stroke 0.3s ease;
  }
  
  .icon-link:hover {
    color: var(--color-accent);
  }
  
  .icon-link:hover svg {
    stroke: var(--color-accent);
  }
  
  /* ===== 页脚 (Footer) ===== */
  .site-footer {
    text-align: center;
    padding: 2rem;
    margin-top: 4rem;
    border-top: 1px solid var(--color-border);
    color: var(--color-text-secondary);
    font-size: 0.9rem;
  }
  
  .site-footer a {
    color: var(--color-text-secondary);
    font-weight: 700;
  }
  
  .site-footer a:hover {
    color: var(--color-accent);
  }
  
  /* ===== 响应式设计 ===== */
  @media (max-width: 600px) {
   .container {
      padding: 2rem 1rem;
    }
  
   .hero-section h1 {
      font-size: 2.5rem;
    }
  
   .research-card {
      padding: 1.5rem;
    }
  }