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

:root {
  --color-bg:        #0d1117;
  --color-surface:   #161b22;
  --color-surface2:  #1c2128;
  --color-border:    #30363d;
  --color-text:      #e6edf3;
  --color-muted:     #8b949e;
  --color-accent:    #58a6ff;
  --color-accent-dim:#1f4068;
  --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  --font-display: 'Cormorant Garamond', 'Garamond', 'Palatino Linotype', Georgia, serif;
  --max-w:    1020px;
  --max-w-sm:  700px;
  --radius:    6px;
}

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

body {
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-sans);
  line-height: 1.7;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* ── Utility ─────────────────────────────────────────────────── */
a { color: var(--color-accent); text-decoration: none; }
a:hover { text-decoration: underline; }
img { max-width: 100%; height: auto; display: block; }

/* ── Buttons ─────────────────────────────────────────────────── */
.btn {
  display: inline-block;
  padding: 0.55rem 1.3rem;
  border-radius: var(--radius);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  transition: opacity 0.15s, background 0.15s;
  border: none;
}
.btn:hover { opacity: 0.85; text-decoration: none; }
.btn-primary { background: var(--color-accent); color: #000; }
.btn-ghost {
  background: transparent;
  color: var(--color-accent);
  border: 1px solid var(--color-accent);
}
.btn-ghost:hover { background: var(--color-accent-dim); }

/* ── Layout shell ────────────────────────────────────────────── */
#site-header { width: 100%; border-bottom: 1px solid var(--color-border); }
#content     { flex: 1; }
#site-footer { border-top: 1px solid var(--color-border); }

/* ── Header / Nav ────────────────────────────────────────────── */
.nav-inner {
  max-width: var(--max-w);
  margin-inline: auto;
  padding: 0.9rem 1.5rem;
  display: flex;
  align-items: center;
  gap: 2rem;
}
.nav-logo {
  height: 36px;
  width: auto;
  display: inline-block;
  vertical-align: middle;
  flex-shrink: 0;
}

.site-title {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  font-weight: 700;
  font-size: 1rem;
  color: var(--color-text);
  white-space: nowrap;
}
.site-title:hover { color: var(--color-accent); text-decoration: none; }

.nav-links {
  display: flex;
  list-style: none;
  gap: 1.75rem;
  margin-left: auto;
}
.nav-links a {
  color: var(--color-muted);
  font-size: 0.9rem;
  font-weight: 500;
  text-decoration: none;
  padding-bottom: 2px;
  border-bottom: 2px solid transparent;
  transition: color 0.15s, border-color 0.15s;
}
.nav-links a:hover,
.nav-links a.active {
  color: var(--color-text);
  border-bottom-color: var(--color-accent);
}
.nav-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--color-text);
  font-size: 1.4rem;
  cursor: pointer;
  margin-left: auto;
  padding: 0.2rem;
}

/* ── Footer ──────────────────────────────────────────────────── */
#site-footer {
  max-width: var(--max-w);
  margin-inline: auto;
  padding: 1.75rem 1.5rem;
  color: var(--color-muted);
  font-size: 0.85rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
}
#site-footer a { color: var(--color-muted); }
#site-footer a:hover { color: var(--color-accent); }

/* ══ HOME PAGE ═══════════════════════════════════════════════════ */

.hero {
  max-width: var(--max-w);
  margin-inline: auto;
  padding: 5rem 1.5rem 4rem;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: center;
}
.hero-text h1 {
  font-family: var(--font-display);
  font-size: clamp(2rem, 3.4vw, 2.8rem);
  font-weight: 700;
  letter-spacing: 0.01em;
  line-height: 1.15;
  margin-bottom: 1rem;
  white-space: nowrap;
}
.hero-subtitle {
  color: var(--color-muted);
  font-size: 1.05rem;
  line-height: 1.5;
  margin-bottom: 0.5rem;
}
.hero-byline {
  color: var(--color-muted);
  font-size: 0.9rem;
  margin-bottom: 2rem;
}
.hero-cta { display: flex; gap: 0.75rem; flex-wrap: wrap; }
.hero-image { display: flex; justify-content: center; align-items: center; background: #000; }
.hero-image img {
  border-radius: var(--radius);
  max-height: 420px;
  width: 100%;
  object-fit: contain;
}

.abstract-strip {
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
  padding: 2.5rem 1.5rem;
}
.abstract-strip p {
  max-width: var(--max-w-sm);
  margin-inline: auto;
  color: var(--color-muted);
  font-size: 1rem;
  line-height: 1.75;
}
.abstract-strip em { color: var(--color-text); font-style: normal; }

.features {
  max-width: var(--max-w);
  margin-inline: auto;
  padding: 4rem 1.5rem;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}
.feature-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.75rem;
}
.feature-icon { font-size: 1.6rem; margin-bottom: 0.75rem; line-height: 1; }
.feature-card h3 { font-size: 1rem; font-weight: 700; margin-bottom: 0.6rem; }
.feature-card p { color: var(--color-muted); font-size: 0.9rem; line-height: 1.65; }

.predictions {
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
  padding: 4rem 1.5rem;
}
.predictions h2 {
  max-width: var(--max-w);
  margin-inline: auto;
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 2rem;
}
.pred-grid {
  max-width: var(--max-w);
  margin-inline: auto;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
}
.pred-item {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.1rem 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
}
.pred-label {
  font-size: 0.78rem;
  color: var(--color-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.pred-value {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--color-accent);
  font-family: var(--font-mono);
}
.pred-note { font-size: 0.8rem; color: var(--color-muted); }

/* ══ INNER PAGES ═════════════════════════════════════════════════ */

.page {
  max-width: var(--max-w-sm);
  margin-inline: auto;
  padding: 3.5rem 1.5rem 5rem;
}
.page-header {
  margin-bottom: 2.25rem;
  padding-bottom: 1.25rem;
  border-bottom: 1px solid var(--color-border);
}
.page-header h1 {
  font-size: clamp(1.8rem, 4vw, 2.4rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  margin-bottom: 0.5rem;
}
.page-desc { color: var(--color-muted); font-size: 0.95rem; line-height: 1.6; }

.page-body h2, .about-body h2 { font-size: 1.25rem; margin: 2rem 0 0.5rem; }
.page-body p, .about-body p   { margin-bottom: 1.1rem; color: var(--color-muted); }
.page-body p:first-child       { color: var(--color-text); }

/* ── Paper page ──────────────────────────────────────────────── */
.page-paper { max-width: var(--max-w); }

.download-bar {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
}
.download-note { color: var(--color-muted); font-size: 0.85rem; }

.pdf-container {
  width: 100%;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  overflow: hidden;
  margin-bottom: 3rem;
  background: var(--color-surface);
}
.pdf-container object { display: block; }

.supplementary { border-top: 1px solid var(--color-border); padding-top: 2rem; }
.supplementary h2 { font-size: 1.15rem; margin-bottom: 0.6rem; }
.supplementary p  { color: var(--color-muted); margin-bottom: 1.25rem; }

/* ── Notebooks page ──────────────────────────────────────────── */
.page-notebooks { max-width: var(--max-w-sm); }

.nb-repo-banner { display: flex; gap: 0.75rem; margin-bottom: 2.5rem; flex-wrap: wrap; }

.notebook-list {
  display: flex;
  flex-direction: column;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  overflow: hidden;
  margin-bottom: 2rem;
}
.nb-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  padding: 1.25rem 1.5rem;
  border-bottom: 1px solid var(--color-border);
}
.nb-row:last-child { border-bottom: none; }
.nb-row:hover { background: var(--color-surface); }

.nb-meta {
  display: flex;
  align-items: flex-start;
  gap: 1.1rem;
  flex: 1;
  min-width: 0;
}
.nb-num {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--color-muted);
  padding-top: 0.2rem;
  white-space: nowrap;
}
.nb-meta h3 { font-size: 0.95rem; font-weight: 700; margin-bottom: 0.25rem; }
.nb-meta p  { font-size: 0.85rem; color: var(--color-muted); margin: 0; }

.nb-actions {
  display: flex;
  gap: 1.25rem;
  align-items: center;
  white-space: nowrap;
  flex-shrink: 0;
  font-size: 0.85rem;
}
.nb-actions a { color: var(--color-accent); }
.nb-actions a:last-child {
  font-weight: 600;
  color: var(--color-text);
}

.nb-footer-note {
  color: var(--color-muted);
  font-size: 0.85rem;
  border-top: 1px solid var(--color-border);
  padding-top: 1.25rem;
}

/* ── About page ──────────────────────────────────────────────── */
.about-body p { margin-bottom: 1.25rem; }
.about-links  { margin-top: 1.75rem; }
.about-links a { font-weight: 600; }

/* ── Contact page ────────────────────────────────────────────── */
.contact-form { display: flex; flex-direction: column; gap: 1.25rem; }
.form-group   { display: flex; flex-direction: column; gap: 0.35rem; }
.form-group label {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-muted);
}
.form-group input,
.form-group textarea {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  color: var(--color-text);
  font-family: var(--font-sans);
  font-size: 0.95rem;
  padding: 0.65rem 0.85rem;
  transition: border-color 0.15s;
  width: 100%;
  resize: vertical;
}
.form-group input:focus,
.form-group textarea:focus { outline: none; border-color: var(--color-accent); }
.form-group input::placeholder,
.form-group textarea::placeholder { color: var(--color-muted); }
.contact-sent {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.5rem;
  color: var(--color-muted);
}

/* reCAPTCHA widget — sits between last textarea and submit button */
.g-recaptcha { margin-top: 0.25rem; }

/* ══ RESPONSIVE ══════════════════════════════════════════════════ */
@media (max-width: 768px) {
  .hero { grid-template-columns: 1fr; padding-top: 3rem; padding-bottom: 2.5rem; gap: 2rem; }
  .hero-image { order: -1; }
  .hero-image img { max-height: 240px; }
  .features { grid-template-columns: 1fr; gap: 1rem; }
  .pred-grid { grid-template-columns: 1fr 1fr; }
  .nb-row { flex-direction: column; align-items: flex-start; gap: 0.75rem; }
  .nb-actions { gap: 1rem; }

  .nav-toggle { display: block; }
  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0; right: 0;
    background: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    flex-direction: column;
    gap: 0;
    padding: 0.5rem 0;
    z-index: 100;
  }
  .nav-links li a { display: block; padding: 0.75rem 1.5rem; border-bottom: none; }
  .nav-inner { position: relative; flex-wrap: wrap; }
  .nav-inner.open .nav-links { display: flex; }
  #site-footer { flex-direction: column; text-align: center; }
}
@media (max-width: 480px) {
  .pred-grid { grid-template-columns: 1fr; }
}