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

:root {
  --sidebar-w: 260px;
  --sidebar-bg: #0f172a;
  --sidebar-text: #94a3b8;
  --sidebar-hover: #1e293b;
  --sidebar-active-bar: #3b82f6;
  --sidebar-active-bg: rgba(59,130,246,0.1);
  --bg: #ffffff;
  --text: #1e293b;
  --text-muted: #64748b;
  --border: #e2e8f0;
  --code-bg: #f8fafc;
  --link: #2563eb;
  --tag-bg: #eff6ff;
  --tag-text: #1d4ed8;
}

html, body {
  height: 100%;
  overflow: hidden;
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background: var(--bg);
  color: var(--text);
  font-size: 15px;
}

/* ── Layout ── */
.layout { display: flex; height: 100vh; }

/* ── Sidebar ── */
.sidebar {
  width: var(--sidebar-w);
  min-width: var(--sidebar-w);
  background: var(--sidebar-bg);
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 0; left: 0; bottom: 0;
  overflow-y: auto;
  z-index: 100;
}

.sidebar-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 16px;
  border-bottom: 1px solid rgba(255,255,255,0.07);
  flex-shrink: 0;
}

.brand {
  color: #f1f5f9;
  font-size: 16px;
  font-weight: 700;
  text-decoration: none;
  letter-spacing: -0.2px;
}

.menu-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--sidebar-text);
  font-size: 20px;
  cursor: pointer;
  padding: 4px;
  line-height: 1;
}

.nav { padding: 10px 0; flex: 1; }

.nav-item {
  display: block;
  padding: 9px 16px;
  color: var(--sidebar-text);
  text-decoration: none;
  border-left: 3px solid transparent;
  transition: background 0.1s, color 0.1s;
}
.nav-item:hover { background: var(--sidebar-hover); color: #e2e8f0; }
.nav-item.active {
  background: var(--sidebar-active-bg);
  border-left-color: var(--sidebar-active-bar);
  color: #f1f5f9;
}

.nav-item-title { font-size: 13px; font-weight: 500; line-height: 1.4; margin-bottom: 2px; }
.nav-item-meta  { font-size: 11px; color: #475569; }

.nav-section {
  padding: 14px 16px 4px;
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: #334155;
}

/* ── Main ── */
.main {
  margin-left: var(--sidebar-w);
  flex: 1;
  overflow-y: auto;
  background: var(--bg);
  display: flex;
  flex-direction: column;
}

.content {
  max-width: 780px;
  margin: 0 auto;
  padding: 52px 40px;
  flex: 1;
}

/* ── Paper page layout (text + sticky TOC side by side) ── */
.paper-topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 32px;
}

.back-btn {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  color: var(--text-muted);
  font-size: 13px;
  text-decoration: none;
  padding: 5px 10px;
  border-radius: 5px;
  transition: background 0.1s, color 0.1s;
}
.back-btn:hover { background: var(--code-bg); color: var(--text); }

.paper-body {
  min-width: 0;
}

/* ── Floating TOC (fixed left, vertically centered) ── */
.toc-float {
  display: none;
  position: fixed;
  left: calc(50vw - 430px);
  top: 50%;
  transform: translateY(-50%);
  width: 160px;
  max-height: 70vh;
  overflow-y: auto;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--code-bg);
  padding: 10px 0;
  z-index: 50;
}

/* Show TOC when there's room left of the content: sidebar(260) + content(780) + margins + TOC(160) ≈ 1420px */
@media (min-width: 1420px) {
  .toc-float { display: block; }
}

/* Ensure hidden attribute always takes effect even when media query overrides display */
.toc-float[hidden] { display: none !important; }

.toc-float-title {
  padding: 4px 12px 8px;
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
  border-bottom: 1px solid var(--border);
  margin-bottom: 4px;
}

.toc-item {
  display: block;
  padding: 4px 12px;
  font-size: 12px;
  color: var(--text-muted);
  text-decoration: none;
  line-height: 1.5;
  border-left: 2px solid transparent;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  transition: color 0.1s, border-color 0.1s;
}
.toc-item:hover { color: var(--text); }
.toc-item.active { color: var(--link); border-left-color: var(--link); }

/* ── Language switcher (top-right) ── */
.lang-switcher { display: flex; gap: 4px; }

.lang-btn {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 4px 10px;
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
  color: var(--text-muted);
  transition: background 0.1s, color 0.1s, border-color 0.1s;
}
.lang-btn:hover { border-color: var(--link); color: var(--link); }
.lang-btn.active { background: var(--link); border-color: var(--link); color: #fff; }

/* ── Like button (bottom of report) ── */
.paper-footer {
  margin-top: 56px;
  padding-top: 24px;
  border-top: 1px solid var(--border);
  display: flex;
  justify-content: center;
}

.like-btn-paper {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: none;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 8px 20px;
  font-size: 14px;
  cursor: pointer;
  color: var(--text-muted);
  transition: border-color 0.15s, color 0.15s, background 0.15s;
}
.like-btn-paper:hover { border-color: #f87171; color: #ef4444; background: #fff5f5; }
.like-btn-paper.liked { border-color: #ef4444; color: #ef4444; background: #fff5f5; }

/* ── Home page ── */
.home-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  margin-bottom: 36px;
}
.home-title  { font-size: 26px; font-weight: 700; color: var(--text); margin-bottom: 6px; }
.home-subtitle { color: var(--text-muted); font-size: 14px; }

.personal-site-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 7px 14px;
  font-size: 13px;
  font-weight: 500;
  color: var(--text-muted);
  border: 1px solid var(--border);
  border-radius: 6px;
  text-decoration: none;
  white-space: nowrap;
  transition: border-color 0.15s, color 0.15s, background 0.15s;
}
.personal-site-btn:hover {
  border-color: var(--link);
  color: var(--link);
  background: #eff6ff;
}
.papers-list { display: flex; flex-direction: column; gap: 12px; }

/* Paper card */
.paper-card {
  display: flex;
  align-items: flex-start;
  gap: 20px;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 16px 20px;
  text-decoration: none;
  color: inherit;
  transition: border-color 0.15s, box-shadow 0.15s;
}
.paper-card:hover {
  border-color: #93c5fd;
  box-shadow: 0 2px 10px rgba(37,99,235,0.08);
}

.paper-card-date {
  font-size: 12px;
  color: var(--text-muted);
  white-space: nowrap;
  min-width: 72px;
  padding-top: 3px;
  font-variant-numeric: tabular-nums;
}

.paper-card-body { flex: 1; min-width: 0; }

.paper-card-title-row {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  margin-bottom: 4px;
}

.paper-card-title { flex: 1; font-size: 15px; font-weight: 600; color: var(--text); line-height: 1.4; }
.paper-card-meta  { font-size: 12px; color: var(--text-muted); margin-bottom: 6px; }
.paper-card-summary { font-size: 13px; color: var(--text-muted); line-height: 1.6; margin-bottom: 8px; }

.tags { display: flex; flex-wrap: wrap; gap: 5px; }
.tag  { background: var(--tag-bg); color: var(--tag-text); font-size: 11px; font-weight: 500; padding: 2px 8px; border-radius: 4px; }

/* Like button on cards */
.like-btn {
  background: none;
  border: none;
  cursor: pointer;
  font-size: 16px;
  padding: 0 2px;
  line-height: 1;
  color: #cbd5e1;
  flex-shrink: 0;
  transition: color 0.15s, transform 0.1s;
}
.like-btn:hover { color: #f87171; transform: scale(1.2); }
.like-btn.liked { color: #ef4444; }

/* ── Markdown rendering ── */
.paper-body h1 { font-size: 24px; font-weight: 700; margin: 0 0 28px; line-height: 1.3; }
.paper-body h2 { font-size: 18px; font-weight: 600; margin: 40px 0 14px; }
.paper-body h3 { font-size: 15px; font-weight: 600; margin: 28px 0 10px; }
.paper-body h4 { font-size: 14px; font-weight: 600; margin: 20px 0 8px; }
.paper-body p  { margin: 0 0 16px; line-height: 1.8; }

.paper-body a       { color: var(--link); text-decoration: none; }
.paper-body a:hover { text-decoration: underline; }

.paper-body ul, .paper-body ol { margin: 0 0 16px 22px; }
.paper-body li             { margin-bottom: 6px; line-height: 1.75; }
.paper-body li > ul,
.paper-body li > ol        { margin-top: 6px; margin-bottom: 0; }

.paper-body code {
  background: var(--code-bg);
  border: 1px solid var(--border);
  padding: 1px 5px;
  border-radius: 4px;
  font-size: 13px;
  font-family: 'SF Mono', 'Fira Code', Consolas, monospace;
}

.paper-body pre {
  background: #1e293b;
  border-radius: 8px;
  padding: 18px;
  margin: 0 0 18px;
  overflow-x: auto;
}
.paper-body pre code { background: none; border: none; padding: 0; font-size: 13px; color: #e2e8f0; }

.paper-body blockquote {
  border-left: 3px solid var(--border);
  margin: 0 0 16px;
  padding: 8px 16px;
  color: var(--text-muted);
}

.paper-body img { max-width: 100%; border-radius: 6px; display: block; margin: 12px auto; }

.paper-body table { width: 100%; border-collapse: collapse; margin: 0 0 18px; font-size: 14px; }
.paper-body th    { background: var(--code-bg); font-weight: 600; padding: 9px 12px; text-align: left; border: 1px solid var(--border); white-space: nowrap; }
.paper-body td    { padding: 8px 12px; border: 1px solid var(--border); line-height: 1.6; }
.paper-body td:first-child       { white-space: nowrap; }
.paper-body tr:nth-child(even) td { background: #f8fafc; }

.paper-body hr { border: none; border-top: 1px solid var(--border); margin: 36px 0; }
.paper-body .katex-display { overflow-x: auto; padding: 4px 0; }

/* ── Site footer ── */
.site-footer {
  text-align: center;
  padding: 24px 40px;
  font-size: 12px;
  color: var(--text-muted);
  margin-top: auto;
}

/* ── Empty state ── */
.empty-state { text-align: center; padding: 80px 0; color: var(--text-muted); }
.empty-state p { margin-top: 8px; font-size: 14px; }

/* ── Responsive ── */
@media (max-width: 768px) {
  .menu-toggle { display: block; }
  .sidebar { width: 100%; height: auto; position: static; min-width: unset; }
  .nav { display: none; }
  .nav.open { display: block; }
  .layout { flex-direction: column; height: auto; }
  .main { margin-left: 0; overflow-y: visible; }
  .content { padding: 28px 20px; }
  .paper-card-date { min-width: 56px; }
  html, body { overflow: auto; }
}