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

:root {
  --white:       #ffffff;
  --off-white:   #f9f8f6;
  --ink:         #1a1a18;
  --ink-mid:     #3d3d39;
  --ink-light:   #6b6b65;
  --rule:        #e2e0da;
  --accent:      #1a3a5c;
  --accent-hover:#0f2640;

  --font-serif:  'EB Garamond', Georgia, serif;
  --font-sans:   'DM Sans', system-ui, sans-serif;

  --max-w:       860px;
  --section-gap: 4rem;
}

html { scroll-behavior: smooth; font-size: 17px; }

body {
  background: var(--white);
  color: var(--ink);
  font-family: var(--font-sans);
  font-weight: 300;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main { flex: 1; }

/* ── Nav ──────────────────────────────────────────────────── */
header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255,255,255,0.93);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--rule);
}

nav {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 1rem 2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 2rem;
}

.nav-name {
  font-family: var(--font-serif);
  font-size: 1.05rem;
  font-weight: 500;
  color: var(--ink);
  text-decoration: none;
  white-space: nowrap;
}

nav ul {
  list-style: none;
  display: flex;
  gap: 2rem;
}

nav ul a {
  font-size: 0.8rem;
  font-weight: 400;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink-light);
  text-decoration: none;
  transition: color 0.15s;
  padding-bottom: 2px;
  border-bottom: 1px solid transparent;
  transition: color 0.15s, border-color 0.15s;
}

nav ul a:hover,
nav ul a.active {
  color: var(--accent);
  border-color: var(--accent);
}

/* ── Page header (non-home pages) ─────────────────────────── */
.page-header {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 3.5rem 2rem 2rem;
  border-bottom: 1px solid var(--rule);
  margin-bottom: 3rem;
}

.page-header h1 {
  font-family: var(--font-serif);
  font-size: 2.2rem;
  font-weight: 500;
  letter-spacing: -0.01em;
}

.page-header p {
  color: var(--ink-mid);
  margin-top: 0.4rem;
  font-family: var(--font-serif);
  font-style: italic;
  font-size: 1.05rem;
}

/* ── Content wrapper ──────────────────────────────────────── */
.content {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 2rem var(--section-gap);
}

/* ── Buttons ──────────────────────────────────────────────── */
.btn-primary, .btn-secondary {
  display: inline-block;
  padding: 0.55rem 1.4rem;
  font-size: 0.8rem;
  font-weight: 400;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  text-decoration: none;
  border-radius: 2px;
  transition: background 0.15s, color 0.15s, border-color 0.15s;
}

.btn-primary {
  background: var(--accent);
  color: var(--white);
  border: 1px solid var(--accent);
}

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

.btn-secondary {
  background: transparent;
  color: var(--accent);
  border: 1px solid var(--accent);
}

.btn-secondary:hover { background: var(--accent); color: var(--white); }

/* ── Divider ──────────────────────────────────────────────── */
.divider {
  border: none;
  border-top: 1px solid var(--rule);
  margin: var(--section-gap) 0;
}

/* ── Section headings ─────────────────────────────────────── */
.section-title {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  font-weight: 500;
  margin-bottom: 1.5rem;
}

.subsection-title {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-weight: 500;
  margin-bottom: 1.2rem;
  margin-top: 2.5rem;
  color: var(--ink);
}

/* ── Paper list ───────────────────────────────────────────── */
.paper-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0;
}

.paper {
  padding: 1.8rem 0;
  border-bottom: 1px solid var(--rule);
}

.paper:first-child { border-top: 1px solid var(--rule); }

.paper-title {
  display: flex;
  align-items: baseline;
  gap: 1rem;
  margin-bottom: 0.35rem;
  flex-wrap: wrap;
}

.paper-title a,
.paper-title .paper-name {
  font-family: var(--font-serif);
  font-size: 1.05rem;
  font-weight: 500;
  color: var(--ink);
  text-decoration: none;
  transition: color 0.15s;
}

.paper-title a:hover { color: var(--accent); }

.paper-year {
  font-size: 0.82rem;
  color: var(--ink-light);
  white-space: nowrap;
}

.paper-meta {
  font-size: 0.9rem;
  color: var(--ink-mid);
  margin-bottom: 0.6rem;
}

.paper-links {
  display: flex;
  gap: 1.2rem;
}

.paper-links a {
  font-size: 0.78rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 0.15s;
}

.paper-links a:hover { border-color: var(--accent); }

/* ── Footer ───────────────────────────────────────────────── */
footer {
  border-top: 1px solid var(--rule);
  padding: 1.8rem 2rem;
  text-align: center;
  font-size: 0.82rem;
  color: var(--ink-light);
}

footer a { color: var(--ink-light); text-decoration: none; }
footer a:hover { color: var(--accent); }

/* ── Animations (opt-in via JS) ───────────────────────────── */
.fade-in {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ── Responsive ───────────────────────────────────────────── */
@media (max-width: 680px) {
  /* Slightly larger base size: every rem-based size scales up with it */
  html { font-size: 18px; }
  body { overflow-wrap: break-word; }
  :root { --section-gap: 3rem; }

  /* Nav: name on top, links centred underneath, never wider than the screen */
  nav {
    flex-direction: column;
    gap: 0.35rem;
    padding: 0.7rem 1rem 0.6rem;
  }
  nav ul {
    flex-wrap: wrap;
    justify-content: center;
    gap: 0.2rem 1.4rem;
  }
  nav ul a {
    display: inline-block;
    font-size: 0.74rem;
    letter-spacing: 0.05em;
    padding: 0.3rem 0 0.15rem;
  }

  .page-header { padding: 2.2rem 1.25rem 1.4rem; margin-bottom: 2rem; }
  .page-header h1 { font-size: 2rem; }
  .content { padding: 0 1.25rem var(--section-gap); }

  .section-title { font-size: 1.6rem; }

  .paper { padding: 1.4rem 0; }
  .paper-title a,
  .paper-title .paper-name { font-size: 1.15rem; line-height: 1.4; }
  .paper-meta { font-size: 0.95rem; }
  .paper-links { flex-wrap: wrap; }
  .paper-links a { font-size: 0.82rem; padding: 0.3rem 0; }

  /* Full-width buttons are easier to tap */
  .btn-primary, .btn-secondary {
    display: block;
    text-align: center;
    padding: 0.8rem 1.4rem;
    font-size: 0.85rem;
  }

  footer { padding: 1.6rem 1.25rem; }
}