:root {
  --void: #08080d;
  --ink: #0d0e16;
  --thread: #6b7bab;
  --crystal: #9186d6;
  --probability: #c093c9;
  --spacetime: #4fa3a0;
  --gravity: #cf9552;
  --octonion: #d9b544;
  --symmetry: #c98a4f;
  --field: #d6684f;
  --matter: #f4efe2;
  --paper: #e8e6ef;
  --paper-dim: #9a97ab;
  --rule: rgba(232, 230, 239, 0.14);
  --font-display: "Palatino Linotype", Palatino, "Book Antiqua", "URW Palladio L", Georgia, serif;
  --font-body: Georgia, "Iowan Old Style", "Palatino Linotype", serif;
  --font-mono: "SF Mono", "Cascadia Code", Consolas, ui-monospace, "Courier New", monospace;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--void);
  color: var(--paper);
  overflow-x: hidden;
  font-family: var(--font-body);
}

::selection { background: var(--octonion); color: #14110a; }

a { color: inherit; }

.skip { position: absolute; left: -9999px; }
.skip:focus {
  left: 1rem; top: 1rem; z-index: 999;
  background: var(--matter); color: var(--void);
  padding: 0.5rem 0.9rem; border-radius: 3px;
}

:focus-visible {
  outline: 2px solid var(--octonion);
  outline-offset: 3px;
}

/* ---------- top nav (detail pages) ---------- */

.topnav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1.1rem 7vw;
  border-bottom: 1px solid var(--rule);
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 0.04em;
  position: sticky;
  top: 0;
  background: rgba(8, 8, 13, 0.86);
  backdrop-filter: blur(6px);
  z-index: 50;
}

.topnav a {
  text-decoration: none;
  color: var(--paper-dim);
  transition: color 0.2s ease;
}

.topnav a:hover, .topnav a:focus-visible { color: var(--matter); }

.topnav .brand {
  color: var(--paper);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  font-size: 0.72rem;
}

/* ---------- hero (index) ---------- */

header.hero {
  min-height: 62vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: flex-start;
  gap: 1.4rem;
  padding: 8vh 7vw 10vh;
  position: relative;
  border-bottom: 1px solid var(--rule);
}

.eyebrow {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--thread);
}

.back-link {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.05em;
  color: var(--thread);
  opacity: 0.85;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 0.4em;
}
.back-link:hover { color: var(--octonion); opacity: 1; }

h1.title {
  font-family: var(--font-display);
  font-weight: 400;
  font-size: clamp(2.6rem, 6vw, 5rem);
  line-height: 1.02;
  margin: 0;
  max-width: 16ch;
  text-wrap: balance;
  color: var(--matter);
  font-style: italic;
  letter-spacing: 0.002em;
}

.hero p.lede {
  font-size: clamp(1.05rem, 1.6vw, 1.28rem);
  max-width: 52ch;
  line-height: 1.6;
  color: var(--paper-dim);
  margin: 0;
}

.hero .honest {
  max-width: 56ch;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  line-height: 1.65;
  color: var(--paper-dim);
  border-left: 2px solid var(--gravity);
  padding-left: 1rem;
  margin-top: 0.6rem;
}

main { position: relative; }

/* ---------- stratum sections (index, clickable) ---------- */

.stratum {
  position: relative;
  min-height: 68vh;
  display: flex;
  align-items: center;
  border-bottom: 1px solid var(--rule);
  overflow: hidden;
}

a.stratum {
  text-decoration: none;
  color: inherit;
  cursor: pointer;
}

.stratum canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  display: block;
}

.stratum .scrim {
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, rgba(0,0,0,0.35) 0%, rgba(0,0,0,0.05) 30%, rgba(0,0,0,0.35) 100%);
  pointer-events: none;
}

.stratum .content {
  position: relative;
  z-index: 2;
  width: min(680px, 84vw);
  margin: 0 7vw;
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.9s ease, transform 0.9s ease;
}

.stratum.in-view .content {
  opacity: 1;
  transform: translateY(0);
}

.stratum .mark {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  letter-spacing: 0.02em;
  display: inline-flex;
  align-items: baseline;
  gap: 0.6rem;
  margin-bottom: 0.9rem;
  color: var(--accent, var(--matter));
}

.stratum .mark .num {
  font-size: 0.72rem;
  color: var(--paper-dim);
  letter-spacing: 0.14em;
}

.stratum .symbol {
  font-size: 1.05rem;
  padding: 0.15rem 0.55rem;
  border: 1px solid var(--accent, var(--matter));
  border-radius: 2px;
}

.stratum h2 {
  font-family: var(--font-display);
  font-weight: 400;
  font-style: italic;
  font-size: clamp(1.7rem, 3.4vw, 2.5rem);
  line-height: 1.12;
  margin: 0 0 0.7rem;
  color: var(--matter);
  text-wrap: balance;
}

.stratum p {
  font-size: clamp(1rem, 1.3vw, 1.14rem);
  line-height: 1.65;
  color: var(--paper-dim);
  max-width: 46ch;
  margin: 0;
}

.stratum p em {
  color: var(--paper);
  font-style: normal;
  border-bottom: 1px solid var(--accent, var(--matter));
}

.stratum .enter {
  margin-top: 1.1rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent, var(--matter));
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  opacity: 0.85;
  transition: gap 0.25s ease, opacity 0.25s ease;
}

a.stratum:hover .enter,
a.stratum:focus-visible .enter {
  gap: 0.9rem;
  opacity: 1;
}

footer.coda {
  padding: 9vh 7vw 12vh;
  display: flex;
  flex-direction: column;
  gap: 1rem;
  max-width: 60ch;
}

footer.coda .eyebrow { margin-bottom: 0.4rem; }

footer.coda p {
  font-size: 0.95rem;
  line-height: 1.7;
  color: var(--paper-dim);
  margin: 0;
}

footer.coda p.small {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--paper-dim);
  opacity: 0.8;
}

/* ---------- detail pages ---------- */

header.detail-hero {
  position: relative;
  min-height: 46vh;
  display: flex;
  align-items: flex-end;
  border-bottom: 1px solid var(--rule);
  overflow: hidden;
}

header.detail-hero canvas {
  position: absolute; inset: 0; width: 100%; height: 100%;
}

header.detail-hero .scrim {
  position: absolute; inset: 0;
  background: linear-gradient(180deg, rgba(0,0,0,0.25) 0%, rgba(0,0,0,0.55) 100%);
}

header.detail-hero .content {
  position: relative;
  z-index: 2;
  padding: 6vh 7vw;
  width: 100%;
}

header.detail-hero .mark {
  font-family: var(--font-mono);
  font-size: 1rem;
  display: inline-flex;
  align-items: baseline;
  gap: 0.6rem;
  margin-bottom: 1rem;
  color: var(--accent, var(--matter));
}

header.detail-hero .mark .num {
  font-size: 0.75rem;
  color: var(--paper-dim);
  letter-spacing: 0.14em;
}

header.detail-hero .symbol {
  font-size: 1.1rem;
  padding: 0.15rem 0.55rem;
  border: 1px solid var(--accent, var(--matter));
  border-radius: 2px;
}

header.detail-hero h1 {
  font-family: var(--font-display);
  font-style: italic;
  font-weight: 400;
  font-size: clamp(2.2rem, 5vw, 4rem);
  margin: 0 0 0.5rem;
  color: var(--matter);
  text-wrap: balance;
  max-width: 20ch;
}

header.detail-hero p.tagline {
  font-size: clamp(1rem, 1.4vw, 1.2rem);
  color: var(--paper-dim);
  max-width: 48ch;
  margin: 0;
  line-height: 1.55;
}

article.body {
  max-width: 68ch;
  margin: 0 auto;
  padding: 8vh 1.75rem 4vh;
}

article.body p {
  font-size: clamp(1.08rem, 1.1vw, 1.2rem);
  line-height: 1.7;
  color: var(--paper);
  margin: 0 0 1.4rem;
}

article.body p.gloss {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  line-height: 1.7;
  color: var(--paper-dim);
  border-left: 2px solid var(--accent, var(--gravity));
  padding-left: 1rem;
  margin: 1.8rem 0;
}

article.body em { color: var(--accent, var(--matter)); font-style: italic; }

article.body h2 {
  font-family: var(--font-display);
  font-style: italic;
  font-weight: 400;
  font-size: clamp(1.3rem, 2.2vw, 1.7rem);
  color: var(--matter);
  margin: 2.6rem 0 1rem;
}

.figure {
  max-width: 76ch;
  margin: 5vh auto;
  padding: 0 1.75rem;
}

.figure canvas {
  width: 100%;
  height: 340px;
  display: block;
  border: 1px solid var(--rule);
  border-radius: 4px;
  background: var(--ink);
}

.figure figcaption {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--paper-dim);
  margin-top: 0.7rem;
  line-height: 1.6;
}

nav.pager {
  display: grid;
  grid-template-columns: 1fr 1fr;
  border-top: 1px solid var(--rule);
  margin-top: 6vh;
}

nav.pager a {
  padding: 2.4rem 7vw;
  text-decoration: none;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  transition: background 0.2s ease;
}

nav.pager a:hover, nav.pager a:focus-visible { background: rgba(255,255,255,0.03); }

nav.pager a.next { text-align: right; align-items: flex-end; border-left: 1px solid var(--rule); }

nav.pager .dir {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--paper-dim);
}

nav.pager .label {
  font-family: var(--font-display);
  font-style: italic;
  font-size: 1.2rem;
  color: var(--matter);
}

@media (prefers-reduced-motion: reduce) {
  .stratum .content { transition: none; opacity: 1; transform: none; }
}

@media (max-width: 640px) {
  header.hero { min-height: 52vh; padding: 10vh 6vw 8vh; }
  .stratum { min-height: 58vh; }
  nav.pager { grid-template-columns: 1fr; }
  nav.pager a.next { border-left: none; border-top: 1px solid var(--rule); align-items: flex-start; text-align: left; }
}

/* ---------- chapter pages (encyclopedia of the 38 capitoli) ---------- */

.katex { color: var(--matter); font-size: 1.02em; }
.katex-display { overflow-x: auto; overflow-y: hidden; margin: 1.6rem 0; padding-bottom: 2px; }

article.body h3 {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent, var(--thread));
  margin: 2.2rem 0 0.8rem;
}

.chip {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--paper-dim);
  border: 1px solid var(--rule);
  border-radius: 999px;
  padding: 0.25rem 0.7rem;
  margin: 0 0.5rem 0.5rem 0;
}

.keybox, .warnbox {
  max-width: 68ch;
  margin: 3vh auto;
  padding: 1.4rem 1.75rem;
  border-radius: 6px;
  border: 1px solid var(--rule);
}

.keybox {
  background: rgba(255,255,255,0.02);
  border-left: 3px solid var(--accent, var(--thread));
}

.keybox h3, .warnbox h3 { margin-top: 0; color: var(--matter); }

.keybox ul { margin: 0; padding-left: 1.2rem; }
.keybox li {
  font-size: 0.98rem;
  line-height: 1.6;
  color: var(--paper-dim);
  margin-bottom: 0.55rem;
}

.warnbox {
  background: rgba(207,149,82,0.06);
  border-left: 3px solid var(--gravity);
}

.warnbox p {
  font-family: var(--font-mono);
  font-size: 0.83rem;
  line-height: 1.7;
  color: var(--paper-dim);
  margin: 0;
}

/* ---------- table of contents (index page, all 38 chapters) ---------- */

.toc {
  padding: 6vh 7vw 4vh;
  border-top: 1px solid var(--rule);
}

.toc > .eyebrow { display: block; margin-bottom: 0.6rem; }

.toc > h2 {
  font-family: var(--font-display);
  font-style: italic;
  font-weight: 400;
  font-size: clamp(1.8rem, 3.4vw, 2.6rem);
  color: var(--matter);
  margin: 0 0 0.8rem;
}

.toc > p.lede {
  max-width: 62ch;
  color: var(--paper-dim);
  line-height: 1.65;
  margin: 0 0 4vh;
}

.toc-part {
  margin-bottom: 4vh;
}

.toc-part h3 {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--thread);
  border-bottom: 1px solid var(--rule);
  padding-bottom: 0.6rem;
  margin: 0 0 1rem;
}

.toc-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 0.4rem 1.4rem;
}

.toc-grid a {
  display: flex;
  align-items: baseline;
  gap: 0.6rem;
  text-decoration: none;
  padding: 0.55rem 0;
  border-bottom: 1px dashed var(--rule);
  color: var(--paper-dim);
  transition: color 0.15s ease, padding-left 0.15s ease;
}

.toc-grid a:hover, .toc-grid a:focus-visible {
  color: var(--matter);
  padding-left: 0.3rem;
}

.toc-grid .n {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--paper-dim);
  min-width: 1.6rem;
}

.toc-grid .t {
  font-family: var(--font-body);
  font-size: 0.98rem;
  color: inherit;
}

/* ---------- footer di sito (comune a tutte le pagine) ---------- */

footer.site-footer {
  padding: 3.5vh 7vw;
  border-top: 1px solid var(--rule);
  text-align: center;
}

footer.site-footer p {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  letter-spacing: 0.03em;
  color: var(--paper-dim);
  opacity: 0.75;
  margin: 0;
}