/* ─── Variables ─────────────────────────────────────────────── */
:root {
  --bg:         #f5f1ea;
  --bg-card:    #fdfaf5;
  --bg-input:   #ffffff;
  --ink:        #1a1714;
  --ink-mid:    #4a4540;
  --ink-soft:   #8a8278;
  --accent:     #b5440f;
  --accent-2:   #d4691e;
  --border:     #ddd8ce;
  --border-mid: #c8c2b6;
  --pill-bg:    #ede8df;
  --pill-active:#1a1714;
  --shadow:     0 1px 3px rgba(26,23,20,0.08), 0 4px 16px rgba(26,23,20,0.04);
  --shadow-hover: 0 4px 12px rgba(26,23,20,0.12), 0 12px 40px rgba(26,23,20,0.08);

  --font-serif: 'DM Serif Display', Georgia, serif;
  --font-sans:  'DM Sans', system-ui, sans-serif;
  --font-mono:  'DM Mono', 'Courier New', monospace;
}

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

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

body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--ink);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent-2); }

/* ─── Header ─────────────────────────────────────────────────── */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(245,241,234,0.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 2rem;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-title {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--ink);
  letter-spacing: 0.05em;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.site-title:hover { color: var(--accent); }

.title-icon {
  color: var(--accent);
  font-size: 1rem;
}

.site-nav { display: flex; gap: 1.5rem; }

.nav-link {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-mid);
  transition: color 0.15s;
}
.nav-link:hover { color: var(--accent); }

/* ─── Main ───────────────────────────────────────────────────── */
.site-main {
  flex: 1;
  max-width: 1100px;
  width: 100%;
  margin: 0 auto;
  padding: 0 2rem;
}

/* ─── Hero ───────────────────────────────────────────────────── */
.hero {
  position: relative;
  padding: 5rem 0 3.5rem;
  overflow: hidden;
}

.hero-inner { position: relative; z-index: 1; }

.hero-label {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 1rem;
}

.hero-title {
  font-family: var(--font-serif);
  font-size: clamp(3rem, 8vw, 5.5rem);
  line-height: 1.0;
  color: var(--ink);
  margin-bottom: 1.5rem;
}
.hero-title em {
  font-style: italic;
  color: var(--accent);
}

.hero-desc {
  font-size: 1.05rem;
  color: var(--ink-mid);
  max-width: 500px;
  line-height: 1.65;
}

.hero-accent {
  position: absolute;
  right: -4rem;
  top: 2rem;
  width: 340px;
  height: 340px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(181,68,15,0.07) 0%, transparent 70%);
  pointer-events: none;
}

/* ─── Search ─────────────────────────────────────────────────── */
.search-section {
  margin-bottom: 1.5rem;
}

.search-wrap {
  position: relative;
  display: flex;
  align-items: center;
  background: var(--bg-input);
  border: 1.5px solid var(--border-mid);
  border-radius: 4px;
  padding: 0 1rem;
  margin-bottom: 0.75rem;
  transition: border-color 0.2s, box-shadow 0.2s;
}
.search-wrap:focus-within {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(181,68,15,0.1);
}

.search-icon {
  font-size: 1.4rem;
  color: var(--ink-soft);
  margin-right: 0.5rem;
  flex-shrink: 0;
  transform: scaleX(-1);
  display: inline-block;
}

.search-input {
  flex: 1;
  border: none;
  outline: none;
  background: transparent;
  font-family: var(--font-sans);
  font-size: 1rem;
  color: var(--ink);
  padding: 0.85rem 0;
}
.search-input::placeholder { color: var(--ink-soft); }

.search-clear {
  cursor: pointer;
  color: var(--ink-soft);
  font-size: 0.75rem;
  padding: 0.25rem;
  opacity: 0;
  transition: opacity 0.15s;
  user-select: none;
}
.search-clear.visible { opacity: 1; }
.search-clear:hover { color: var(--accent); }

.filter-pills {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.pill {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 0.3rem 0.75rem;
  border-radius: 100px;
  border: 1.5px solid var(--border);
  background: var(--pill-bg);
  color: var(--ink-mid);
  cursor: pointer;
  transition: all 0.15s;
}
.pill:hover { border-color: var(--border-mid); color: var(--ink); }
.pill.active {
  background: var(--pill-active);
  border-color: var(--pill-active);
  color: #f5f1ea;
}

/* ─── Results meta ───────────────────────────────────────────── */
.results-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.5rem 0 1rem;
  border-top: 1px solid var(--border);
  margin-bottom: 0.25rem;
}

#results-count {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--ink-soft);
}

.sort-label {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--ink-soft);
}

/* ─── Papers Grid ────────────────────────────────────────────── */
.papers-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1.25rem;
  padding-bottom: 4rem;
}

/* ─── Paper Card ─────────────────────────────────────────────── */
.paper-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 1.5rem;
  position: relative;
  box-shadow: var(--shadow);
  transition: box-shadow 0.2s, transform 0.2s, border-color 0.2s;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  animation: fadeIn 0.3s ease both;
}

.paper-card:hover {
  box-shadow: var(--shadow-hover);
  transform: translateY(-2px);
  border-color: var(--border-mid);
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}

.paper-card.hidden { display: none; }

.card-year {
  position: absolute;
  top: 1.25rem;
  right: 1.25rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--ink-soft);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 3px;
  padding: 0.15rem 0.45rem;
}

.card-title {
  font-family: var(--font-serif);
  font-size: 1.1rem;
  line-height: 1.35;
  color: var(--ink);
  padding-right: 3rem;
}

.card-authors {
  font-size: 0.85rem;
  color: var(--ink-mid);
  line-height: 1.5;
}

.author-tag { white-space: nowrap; }

.card-meta {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.card-venue {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--accent);
  font-weight: 500;
  letter-spacing: 0.03em;
}

.card-doi {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.05em;
  color: var(--ink-soft);
  border: 1px solid var(--border);
  border-radius: 3px;
  padding: 0.1rem 0.4rem;
  transition: all 0.15s;
}
.card-doi:hover {
  color: var(--accent);
  border-color: var(--accent);
  background: rgba(181,68,15,0.04);
}

.card-keywords {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
}

.keyword {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.04em;
  background: var(--pill-bg);
  border: 1px solid var(--border);
  border-radius: 3px;
  padding: 0.15rem 0.45rem;
  color: var(--ink-mid);
}

.keyword.highlight {
  background: rgba(181,68,15,0.1);
  border-color: rgba(181,68,15,0.3);
  color: var(--accent);
}

.card-abstract {
  font-size: 0.83rem;
  color: var(--ink-soft);
  line-height: 1.6;
  border-top: 1px solid var(--border);
  padding-top: 0.75rem;
}

/* ─── No results ─────────────────────────────────────────────── */
.no-results {
  text-align: center;
  padding: 5rem 2rem;
  color: var(--ink-soft);
}

.no-results-icon {
  display: block;
  font-size: 2.5rem;
  margin-bottom: 1rem;
  opacity: 0.4;
}

.no-results p {
  font-size: 1rem;
  margin-bottom: 1.5rem;
}

.no-results button {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 0.5rem 1.25rem;
  background: var(--ink);
  color: var(--bg);
  border: none;
  border-radius: 3px;
  cursor: pointer;
  transition: background 0.15s;
}
.no-results button:hover { background: var(--accent); }

/* ─── About page ─────────────────────────────────────────────── */
.about-page {
  padding: 4rem 0;
}

.about-inner {
  max-width: 660px;
}

.about-title {
  font-family: var(--font-serif);
  font-size: 2.8rem;
  color: var(--ink);
  margin-bottom: 2rem;
}

.about-body h2 {
  font-family: var(--font-serif);
  font-size: 1.3rem;
  margin: 2rem 0 0.75rem;
  color: var(--ink);
}

.about-body p {
  color: var(--ink-mid);
  margin-bottom: 1rem;
  line-height: 1.7;
}

.about-body pre {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 1.25rem;
  overflow-x: auto;
  margin: 1rem 0;
}

.about-body code {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: var(--accent);
  background: rgba(181,68,15,0.07);
  padding: 0.1em 0.35em;
  border-radius: 3px;
}

.about-body pre code {
  background: none;
  color: var(--ink);
  padding: 0;
  font-size: 0.8rem;
  line-height: 1.7;
}

.stats-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--ink-mid);
}

/* ─── Footer ─────────────────────────────────────────────────── */
.site-footer {
  border-top: 1px solid var(--border);
  background: var(--bg);
}

.footer-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 1.25rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--ink-soft);
}

/* ─── Highlight matches ──────────────────────────────────────── */
mark {
  background: rgba(181,68,15,0.15);
  color: var(--accent);
  border-radius: 2px;
  padding: 0 1px;
}

/* ─── Responsive ─────────────────────────────────────────────── */
@media (max-width: 640px) {
  .site-main { padding: 0 1rem; }
  .header-inner { padding: 0 1rem; }
  .footer-inner { padding: 1rem; flex-direction: column; gap: 0.5rem; text-align: center; }
  .hero { padding: 3rem 0 2rem; }
  .hero-accent { display: none; }
  .papers-grid { grid-template-columns: 1fr; }
}