@import url('https://fonts.googleapis.com/css2?family=Newsreader:ital,opsz,wght@0,6..72,300;0,6..72,400;0,6..72,500;1,6..72,300;1,6..72,400&family=JetBrains+Mono:wght@400&display=swap');

:root {
  --ink: #1a1a1a;
  --paper: #f5f3ee;
  --faded: #777;
  --rule: #ccc;
  --accent: #8b4513;
  --highlight: #eae6dc;
}

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

body {
  font-family: 'Newsreader', 'Georgia', serif;
  font-size: 18px;
  line-height: 1.7;
  color: var(--ink);
  background: var(--paper);
  -webkit-font-smoothing: antialiased;
}

.page { max-width: 640px; margin: 0 auto; padding: 60px 24px 120px; }

/* ── Site Nav ── */
.site-nav {
  display: flex; justify-content: space-between; align-items: center;
  font-size: 13px; letter-spacing: 0.1em; text-transform: uppercase;
  padding-bottom: 16px; margin-bottom: 32px; border-bottom: 1px solid var(--rule);
}
.site-nav .site-name { color: var(--ink); text-decoration: none; font-weight: 500; }
.site-nav .site-name:hover { color: var(--accent); }
.site-nav .site-links a { color: var(--faded); text-decoration: none; }
.site-nav .site-links a:hover { color: var(--ink); }
.site-nav .site-links .sep { color: var(--rule); margin: 0 6px; }

/* ── Nav ── */
nav { font-size: 14px; letter-spacing: 0.08em; text-transform: uppercase; margin-bottom: 48px; }
nav a { color: var(--faded); text-decoration: none; border-bottom: 1px solid var(--rule); padding-bottom: 1px; }
nav a:hover { color: var(--ink); border-color: var(--ink); }
nav .sep { color: var(--rule); margin: 0 8px; }

/* ── Headers ── */
header { padding-bottom: 40px; margin-bottom: 40px; border-bottom: 1px solid var(--rule); }
header h1 { font-size: 28px; font-weight: 500; line-height: 1.35; margin-bottom: 12px; letter-spacing: -0.01em; }
header .subtitle { font-size: 18px; font-style: italic; color: var(--faded); margin-bottom: 16px; }
header .meta { font-size: 13px; color: var(--faded); letter-spacing: 0.06em; text-transform: uppercase; }

.index-header { text-align: center; }
.index-header h1 { font-size: 17px; font-weight: 400; letter-spacing: 0.2em; text-transform: uppercase; color: var(--faded); margin-bottom: 28px; }
.index-header .main-title { font-size: 32px; font-weight: 500; line-height: 1.3; margin-bottom: 12px; }
.index-header .subtitle { font-size: 19px; font-style: italic; color: var(--faded); margin-bottom: 20px; }
.index-header .meta { font-size: 14px; color: var(--faded); letter-spacing: 0.06em; text-transform: uppercase; }

/* ── Content ── */
p { margin-bottom: 16px; }
h2 { font-size: 20px; font-weight: 500; margin: 40px 0 16px; }
h2.section-heading { font-size: 14px; font-weight: 500; letter-spacing: 0.15em; text-transform: uppercase; color: var(--accent); margin: 56px 0 24px; padding-top: 24px; border-top: 1px solid var(--rule); }
h3 { font-size: 17px; font-weight: 500; margin: 32px 0 12px; }

.equation { text-align: center; font-size: 28px; font-style: italic; padding: 28px 0; margin: 32px 0; border-top: 1px solid var(--rule); border-bottom: 1px solid var(--rule); letter-spacing: 0.04em; }

.result { background: var(--highlight); padding: 16px 20px; margin: 20px 0; font-size: 17px; line-height: 1.65; }
.result strong { font-weight: 500; }

.math-block { text-align: center; margin: 24px 0; font-size: 19px; font-style: italic; line-height: 2; }

.chain { font-family: 'JetBrains Mono', monospace; font-size: 13px; line-height: 2; background: var(--highlight); padding: 18px 22px; margin: 24px 0; overflow-x: auto; white-space: pre; }

table { width: 100%; border-collapse: collapse; font-size: 16px; margin: 24px 0; }
th { text-align: left; font-weight: 500; font-size: 13px; letter-spacing: 0.06em; text-transform: uppercase; color: var(--faded); padding: 8px 10px; border-bottom: 2px solid var(--rule); }
td { padding: 8px 10px; border-bottom: 1px solid #eee; vertical-align: top; }

/* ── Paper cards (index) ── */
.paper { margin-bottom: 44px; padding-bottom: 44px; border-bottom: 1px solid var(--rule); }
.paper:last-of-type { border-bottom: none; }
.paper-number { font-size: 12px; font-weight: 400; letter-spacing: 0.15em; text-transform: uppercase; color: var(--accent); margin-bottom: 6px; }
.paper h2 { font-size: 21px; margin: 0 0 14px; }
.paper h2 a { color: var(--ink); text-decoration: none; }
.paper h2 a:hover { color: var(--accent); }
.paper p { margin-bottom: 10px; }
.paper .detail { font-size: 16px; color: var(--faded); font-style: italic; }

/* ── Links ── */
.pdf-link, .html-link { display: inline-block; margin-top: 10px; margin-right: 16px; font-size: 13px; letter-spacing: 0.08em; text-transform: uppercase; text-decoration: none; padding-bottom: 2px; transition: opacity 0.2s; }
.pdf-link { color: var(--accent); border-bottom: 1px solid var(--accent); }
.html-link { color: var(--faded); border-bottom: 1px solid var(--rule); }
.pdf-link:hover, .html-link:hover { opacity: 0.7; }

/* ── Theorems (paper pages) ── */
.theorem { background: #f0ecf4; border-left: 3px solid #5b4a7c; padding: 16px 20px; margin: 24px 0; }
.theorem .label { font-weight: 500; font-size: 14px; letter-spacing: 0.06em; text-transform: uppercase; color: #5b4a7c; display: block; margin-bottom: 6px; }

.definition { background: var(--highlight); border-left: 3px solid var(--accent); padding: 16px 20px; margin: 24px 0; }
.definition .label { font-weight: 500; font-size: 14px; letter-spacing: 0.06em; text-transform: uppercase; color: var(--accent); display: block; margin-bottom: 6px; }

.remark { font-size: 16px; color: var(--faded); font-style: italic; margin: 20px 0; padding-left: 20px; border-left: 2px solid var(--rule); }

/* ── Footer ── */
footer { margin-top: 64px; padding-top: 32px; border-top: 1px solid var(--rule); text-align: center; font-size: 15px; color: var(--faded); }
footer .blessing { font-style: italic; margin-top: 20px; line-height: 1.8; color: var(--ink); font-size: 16px; }
footer .contact { margin-top: 20px; font-size: 13px; letter-spacing: 0.05em; }
footer .contact a { color: var(--faded); text-decoration: none; border-bottom: 1px solid var(--rule); }

@media (max-width: 480px) {
  body { font-size: 17px; }
  .page { padding: 36px 18px 80px; }
  header h1, .index-header .main-title { font-size: 25px; }
  .equation { font-size: 24px; }
}