:root {
  /* 背景 */
  --bg-primary: #ffffff;         /* 纯白，主背景 */
  --bg-secondary: #fafafa;       /* 极浅灰，用于 section 交替以保持层次 */
  --bg-card: #ffffff;            /* 卡片背景 */

  /* 文字 */
  --text-primary: #1a1a18;       /* 深色正文 */
  --text-secondary: #5c5b56;     /* 副文字 */
  --text-muted: #8a8985;         /* 弱化文字 */

  /* 强调色 */
  --accent: #d97757;             /* Anthropic 橘色，用于状态标签、hover */
  --accent-light: #f5ddd3;       /* 橘色浅底 */
  --accent-blue: #6a9bcc;        /* 链接色 */

  /* 边框/分割线 */
  --border: #e0dfd8;
  --border-light: #eae9e3;

  /* 阴影 */
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
}

body {
  font-family: 'Inter', -apple-system, 'PingFang SC', 'Noto Sans SC', sans-serif;
  font-size: 16px;
  line-height: 1.7;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  margin: 0;
  padding: 0;
  scroll-behavior: smooth;
}

h1, h2, h3 {
  font-weight: 600;
  line-height: 1.3;
}

a {
  color: var(--accent-blue);
  text-decoration: none;
}
a:hover {
  text-decoration: underline;
}

/* 默认：桌面 */
.container { max-width: 900px; margin: 0 auto; padding: 0 2rem; }

section {
  padding: 4rem 0;
}
section:nth-child(even) {
  background-color: var(--bg-secondary);
}

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

/* 导航栏 */
nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border-light);
  padding: 0.75rem 2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav-links a {
  margin-left: 1.5rem;
  color: var(--text-secondary);
  font-size: 0.9rem;
}
.nav-links a:hover {
  color: var(--text-primary);
  text-decoration: none;
}
.logo-img {
  height: 36px;
  vertical-align: middle;
}

/* Hero Section */
.hero {
  padding: 6rem 0;
}
.hero h1 {
  font-size: 2.5rem;
  margin-bottom: 1rem;
}
.hero p {
  font-size: 1.25rem;
  color: var(--text-secondary);
}

/* 论文卡片 */
.paper-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: 8px;
  padding: 1.5rem;
  margin-bottom: 1rem;
  box-shadow: var(--shadow-sm);
  transition: box-shadow 0.2s ease;
}
.paper-card:hover {
  box-shadow: var(--shadow-md);
}
.paper-title {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
  display: flex;
  align-items: center;
  gap: 10px;
}
.paper-desc {
  font-size: 0.95rem;
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
}

/* 状态标签 */
.tag-preprint {
  background: var(--accent-light);
  color: var(--accent);
  padding: 2px 10px;
  border-radius: 12px;
  font-size: 0.8rem;
  font-weight: 500;
  white-space: nowrap;
}
.tag-in-prep {
  background: #e8e6dc;
  color: var(--text-secondary);
  padding: 2px 10px;
  border-radius: 12px;
  font-size: 0.8rem;
  font-weight: 500;
  white-space: nowrap;
}

/* 关键词标签 */
.keywords {
  margin-top: 2rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  justify-content: center;
}
.keyword-tag {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  padding: 4px 12px;
  border-radius: 16px;
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* B 站视频嵌入（响应式） */
.bilibili-container {
  position: relative;
  width: 100%;
  max-width: 720px;
  aspect-ratio: 16 / 9;
  margin: 1.5rem auto;
}
.bilibili-container iframe {
  position: absolute;
  top: 0; left: 0;
  width: 100%; height: 100%;
  border: 0;
  border-radius: 6px;
}
.video-caption {
  text-align: center;
  font-size: 0.9rem;
  color: var(--text-secondary);
  font-style: italic;
  margin-top: -0.5rem;
  margin-bottom: 2rem;
}

/* 图书展示区域 */
.book-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 2rem;
  margin: 1.5rem 0;
}
.book-item {
  text-align: center;
}
.book-item img {
  width: 100%;
  max-width: 180px;
  border-radius: 4px;
  box-shadow: var(--shadow-md);
  margin-bottom: 1rem;
}
.book-title {
  font-weight: 600;
  font-size: 1rem;
  margin-bottom: 0.25rem;
}
.book-author {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

/* 犯罪小说单独展示 */
.crime-novel {
  text-align: center;
  margin-top: 3rem;
  margin-bottom: 3rem;
}
.crime-novel img {
  max-width: 200px;
  border-radius: 4px;
  box-shadow: var(--shadow-md);
  margin-bottom: 1rem;
}

/* 榜单截图区域 */
.rank-screenshots {
  display: flex;
  gap: 1rem;
  justify-content: center;
  margin: 1.5rem 0;
}
.rank-screenshots figure {
  flex: 1;
  max-width: 220px;
  text-align: center;
  margin: 0;
}
.rank-screenshots img {
  width: 100%;
  border-radius: 8px;
  border: 1px solid var(--border);
  box-shadow: var(--shadow-sm);
}
.rank-screenshots figcaption {
  margin-top: 0.5rem;
  font-size: 0.85rem;
  color: var(--text-secondary);
}
.rank-note {
  text-align: center;
  font-size: 0.85rem;
  color: var(--text-muted);
  font-style: italic;
  margin-top: 1rem;
}

/* Footer */
footer {
  text-align: center;
  padding: 3rem 0;
  background-color: #f5f5f5;
  color: var(--text-secondary);
  font-size: 0.85rem;
}
footer a {
  color: var(--text-secondary);
}

/* 响应式 */
@media (max-width: 768px) {
  .book-grid { grid-template-columns: 1fr; }
  .rank-screenshots { flex-direction: column; align-items: center; }
  .rank-screenshots figure { max-width: 280px; margin-bottom: 1.5rem;}
  nav { flex-direction: column; gap: 1rem; padding: 1rem; }
  .nav-links a { margin: 0 0.5rem; }
}

@media (max-width: 480px) {
  .container { padding: 0 1rem; }
  nav { font-size: 0.9rem; }
  .hero h1 { font-size: 2rem; }
  .paper-title { flex-direction: column; align-items: flex-start; gap: 5px; }
}