/* ===== Reset & Base ===== */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --primary: #2563eb;
  --primary-light: #dbeafe;
  --text: #1e293b;
  --text-secondary: #64748b;
  --bg: #f8fafc;
  --white: #ffffff;
  --border: #e2e8f0;
  --star-filled: #f59e0b;
  --star-empty: #d1d5db;
  --tag-bg: #eff6ff;
  --tag-text: #1d4ed8;
  --shadow: 0 1px 3px rgba(0,0,0,0.08);
  --shadow-lg: 0 4px 12px rgba(0,0,0,0.1);
  --radius: 8px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Noto Sans SC", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  font-size: 15px;
}

a {
  color: var(--primary);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

/* ===== Layout ===== */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* ===== Header ===== */
.site-header {
  background: var(--white);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
}

.site-logo {
  font-size: 18px;
  font-weight: 700;
  color: var(--text);
}

.site-logo:hover {
  text-decoration: none;
  color: var(--primary);
}

.site-nav a {
  margin-left: 24px;
  color: var(--text-secondary);
  font-size: 14px;
}

.site-nav a:hover {
  color: var(--primary);
  text-decoration: none;
}

/* ===== Hero ===== */
.hero {
  text-align: center;
  padding: 48px 0 32px;
}

.hero h1 {
  font-size: 28px;
  font-weight: 700;
  margin-bottom: 8px;
}

.hero p {
  color: var(--text-secondary);
  font-size: 16px;
}

.stats {
  margin-top: 12px;
  color: var(--text-secondary);
  font-size: 14px;
}

.stats strong {
  color: var(--primary);
}

/* ===== Controls ===== */
.controls {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 24px;
  box-shadow: var(--shadow);
}

.search-box {
  margin-bottom: 16px;
}

.search-box input {
  width: 100%;
  padding: 10px 16px;
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 14px;
  outline: none;
  transition: border-color 0.2s;
}

.search-box input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-light);
}

.filter-group {
  margin-bottom: 12px;
}

.filter-group label,
.sort-group label {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-secondary);
  margin-right: 8px;
}

.tag-filters {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 8px;
}

.tag-btn {
  padding: 4px 12px;
  border: 1px solid var(--border);
  border-radius: 20px;
  background: var(--white);
  color: var(--text-secondary);
  font-size: 12px;
  cursor: pointer;
  transition: all 0.2s;
}

.tag-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.tag-btn.active {
  background: var(--primary);
  color: var(--white);
  border-color: var(--primary);
}

.sort-group select {
  padding: 6px 12px;
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 13px;
  outline: none;
  cursor: pointer;
}

/* ===== Table ===== */
.paper-table-wrapper {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
  margin-bottom: 48px;
}

.paper-table {
  width: 100%;
  border-collapse: collapse;
}

.paper-table thead {
  background: #f1f5f9;
}

.paper-table th {
  padding: 12px 16px;
  text-align: left;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-secondary);
  border-bottom: 1px solid var(--border);
  white-space: nowrap;
}

.paper-table td {
  padding: 14px 16px;
  border-bottom: 1px solid var(--border);
  font-size: 14px;
  vertical-align: top;
}

.paper-row:last-child td {
  border-bottom: none;
}

.paper-row:hover {
  background: #f8faff;
}

.paper-title-cell a {
  font-weight: 600;
  font-size: 14px;
}

.paper-summary {
  color: var(--text-secondary);
  font-size: 12px;
  margin-top: 4px;
  line-height: 1.4;
}

.paper-authors {
  color: var(--text-secondary);
  font-size: 13px;
  max-width: 200px;
}

.paper-year {
  font-weight: 500;
  white-space: nowrap;
}

.paper-venue {
  font-size: 13px;
  color: var(--text-secondary);
  white-space: nowrap;
}

/* ===== Tags ===== */
.tag {
  display: inline-block;
  padding: 2px 10px;
  background: var(--tag-bg);
  color: var(--tag-text);
  border-radius: 20px;
  font-size: 11px;
  font-weight: 500;
  margin: 2px 2px;
  white-space: nowrap;
}

/* ===== Stars ===== */
.star {
  color: var(--star-empty);
  font-size: 14px;
}

.star.filled {
  color: var(--star-filled);
}

/* ===== No Results ===== */
.no-results {
  text-align: center;
  padding: 48px 20px;
  color: var(--text-secondary);
  font-size: 15px;
}

/* ===== Paper Detail ===== */
.paper-detail {
  max-width: 800px;
  margin: 0 auto;
  padding: 32px 0 64px;
}

.back-link {
  display: inline-block;
  color: var(--text-secondary);
  font-size: 14px;
  margin-bottom: 24px;
}

.back-link:hover {
  color: var(--primary);
  text-decoration: none;
}

.paper-header {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  margin-bottom: 32px;
  box-shadow: var(--shadow);
}

.paper-header h1 {
  font-size: 24px;
  line-height: 1.4;
  margin-bottom: 20px;
}

.paper-meta {
  margin-bottom: 20px;
}

.meta-row {
  display: flex;
  padding: 8px 0;
  border-bottom: 1px solid var(--border);
}

.meta-row:last-child {
  border-bottom: none;
}

.meta-label {
  flex-shrink: 0;
  width: 90px;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-secondary);
}

.meta-value {
  flex: 1;
  font-size: 14px;
}

.meta-value.summary {
  color: var(--text-secondary);
  font-style: italic;
}

.paper-links {
  display: flex;
  gap: 12px;
}

.btn {
  display: inline-block;
  padding: 8px 20px;
  border-radius: 6px;
  font-size: 13px;
  font-weight: 600;
  transition: all 0.2s;
}

.btn:hover {
  text-decoration: none;
  transform: translateY(-1px);
  box-shadow: var(--shadow-lg);
}

.btn-paper {
  background: var(--primary);
  color: var(--white);
}

.btn-code {
  background: #1e293b;
  color: var(--white);
}

/* ===== Paper Content (Markdown) ===== */
.paper-content {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  box-shadow: var(--shadow);
  margin-bottom: 32px;
}

.paper-content h2 {
  font-size: 20px;
  margin-top: 32px;
  margin-bottom: 12px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}

.paper-content h2:first-child {
  margin-top: 0;
}

.paper-content h3 {
  font-size: 17px;
  margin-top: 24px;
  margin-bottom: 8px;
}

.paper-content p {
  margin-bottom: 12px;
  line-height: 1.8;
}

.paper-content ul, .paper-content ol {
  margin-bottom: 12px;
  padding-left: 24px;
}

.paper-content li {
  margin-bottom: 4px;
  line-height: 1.7;
}

.paper-content code {
  background: #f1f5f9;
  padding: 2px 6px;
  border-radius: 3px;
  font-size: 13px;
}

.paper-content pre {
  background: #1e293b;
  color: #e2e8f0;
  padding: 16px;
  border-radius: 6px;
  overflow-x: auto;
  margin-bottom: 16px;
}

.paper-content pre code {
  background: none;
  padding: 0;
  color: inherit;
}

.paper-content img {
  max-width: 100%;
  border-radius: 6px;
  margin: 16px 0;
}

.paper-content blockquote {
  border-left: 3px solid var(--primary);
  padding: 8px 16px;
  margin: 16px 0;
  background: var(--primary-light);
  border-radius: 0 6px 6px 0;
}

.paper-content table {
  width: 100%;
  border-collapse: collapse;
  margin: 16px 0;
}

.paper-content table th,
.paper-content table td {
  padding: 8px 12px;
  border: 1px solid var(--border);
  text-align: left;
  font-size: 13px;
}

.paper-content table th {
  background: #f1f5f9;
  font-weight: 600;
}

/* ===== Footer ===== */
footer {
  text-align: center;
  padding: 24px 0;
  color: var(--text-secondary);
  font-size: 13px;
  border-top: 1px solid var(--border);
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .hero h1 { font-size: 22px; }

  .paper-table-wrapper {
    overflow-x: auto;
  }

  .paper-table th,
  .paper-table td {
    padding: 10px 12px;
  }

  .paper-authors {
    max-width: 120px;
  }

  .paper-header,
  .paper-content {
    padding: 20px;
  }

  .meta-row {
    flex-direction: column;
  }

  .meta-label {
    width: auto;
    margin-bottom: 2px;
  }
}