/* =========================================================
   Marges — minimal mathematical blog
   Monochrome, ink on warm white. Spectral + IBM Plex Mono.
   ========================================================= */

:root {
  --bg:        oklch(0.991 0.003 95);   /* warm near-white */
  --bg-2:      oklch(0.965 0.004 95);   /* faint panel     */
  --ink:       oklch(0.205 0.006 75);   /* near-black ink  */
  --ink-soft:  oklch(0.205 0.006 75 / 0.62);
  --muted:     oklch(0.205 0.006 75 / 0.42);
  --hair:      oklch(0.205 0.006 75 / 0.12);
  --hair-2:    oklch(0.205 0.006 75 / 0.06);
  --cell:      oklch(0.205 0.006 75);   /* automaton cell  */

  --serif: "Spectral", Georgia, "Times New Roman", serif;
  --mono:  "IBM Plex Mono", ui-monospace, "SFMono-Regular", Menlo, monospace;

  --measure: 40rem;          /* reading width */
  --wide:    52rem;          /* list/wide content */
  --pad:     clamp(1.25rem, 5vw, 2.5rem);

  --t: 420ms cubic-bezier(0.22, 1, 0.36, 1);
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--serif);
  font-size: clamp(1.02rem, 0.97rem + 0.25vw, 1.18rem);
  line-height: 1.62;
  font-weight: 400;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  font-feature-settings: "liga" 1, "onum" 1, "kern" 1;
}

::selection { background: var(--ink); color: var(--bg); }

a { color: inherit; text-decoration: none; }

/* ---------- layout ---------- */
.wrap { width: 100%; max-width: var(--wide); margin: 0 auto; padding-inline: var(--pad); }
.measure { max-width: var(--measure); }

/* ---------- top bar ---------- */
.topbar {
  position: sticky; top: 0; z-index: 20;
  display: flex; align-items: baseline; justify-content: space-between;
  gap: 1rem;
  padding: 1.05rem var(--pad);
  background: color-mix(in oklab, var(--bg) 86%, transparent);
  backdrop-filter: blur(8px) saturate(1.1);
  -webkit-backdrop-filter: blur(8px) saturate(1.1);
  border-bottom: 1px solid var(--hair-2);
}
.brand {
  font-family: var(--serif);
  font-size: 1.25rem;
  font-weight: 500;
  letter-spacing: -0.01em;
  display: inline-flex; align-items: baseline; gap: 0.5rem;
}
.brand .mark { font-style: italic; }
.nav { display: flex; gap: 1.6rem; }
.nav a {
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-soft);
  padding-bottom: 2px;
  border-bottom: 1px solid transparent;
  transition: color var(--t), border-color var(--t);
}
.nav a:hover, .nav a[aria-current="page"] { color: var(--ink); border-color: var(--ink); }

/* ---------- automaton header ---------- */
.hero { position: relative; border-bottom: 1px solid var(--hair); }
.hero canvas {
  display: block; width: 100%;
  height: clamp(170px, 30vh, 280px);
  background: var(--bg);
}
.hero canvas.reveal { animation: caReveal 1100ms cubic-bezier(0.22, 1, 0.36, 1) both; }
@keyframes caReveal {
  from { clip-path: inset(0 0 100% 0); }
  to   { clip-path: inset(0 0 0 0); }
}
/* ---------- masthead ---------- */
.masthead { padding: clamp(2.5rem, 7vw, 4.5rem) 0 clamp(1.5rem, 4vw, 2.5rem); }
.masthead h1 {
  font-weight: 300; font-size: clamp(2.2rem, 1.4rem + 4vw, 4rem);
  line-height: 1.02; letter-spacing: -0.02em; margin: 0 0 0.9rem;
}
.masthead h1 em { font-style: italic; }
.masthead .lede {
  margin: 0; max-width: 34rem; color: var(--ink-soft);
  font-size: clamp(1.05rem, 1rem + 0.4vw, 1.3rem); line-height: 1.5;
}

/* ---------- index list ---------- */
.section-label {
  font-family: var(--mono); font-size: 0.7rem; letter-spacing: 0.18em;
  text-transform: uppercase; color: var(--muted);
  padding: 1.5rem 0 0.4rem; border-top: 1px solid var(--hair);
}
.list { list-style: none; margin: 0 0 5rem; padding: 0; }
.empty {
  font-family: var(--mono); font-size: 0.78rem; letter-spacing: 0.06em;
  color: var(--muted);
  border-top: 1px solid var(--hair);
  padding: 2.5rem 0 6rem; margin: 0;
}
.entry {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: baseline; gap: 0.5rem 1.5rem;
  padding: 1.4rem 0.4rem 1.4rem;
  border-bottom: 1px solid var(--hair);
  position: relative;
  transition: padding var(--t);
}
.entry::before {
  content: ""; position: absolute; left: -0.6rem; top: 0; bottom: 0; width: 1px;
  background: var(--ink); transform: scaleY(0); transform-origin: top;
  transition: transform var(--t);
}
.entry:hover { padding-left: 1rem; }
.entry:hover::before { transform: scaleY(1); }
.entry .e-title {
  font-size: clamp(1.25rem, 1.1rem + 0.7vw, 1.6rem);
  font-weight: 400; line-height: 1.2; letter-spacing: -0.01em;
  grid-column: 1; transition: opacity var(--t);
}
.entry .e-desc {
  grid-column: 1; grid-row: 2; margin: 0.35rem 0 0;
  color: var(--ink-soft); font-size: 0.98rem; line-height: 1.5; max-width: 38rem;
}
.entry .e-date {
  grid-column: 2; grid-row: 1;
  font-family: var(--mono); font-size: 0.74rem; letter-spacing: 0.06em;
  color: var(--muted); white-space: nowrap; padding-top: 0.35rem;
}
.entry .e-tags {
  grid-column: 2; grid-row: 2; justify-self: end;
  font-family: var(--mono); font-size: 0.68rem; letter-spacing: 0.05em;
  color: var(--muted);
}

/* ---------- article ---------- */
.article { padding: clamp(2rem, 6vw, 4rem) 0 6rem; }
.article header { margin-bottom: clamp(2rem, 5vw, 3.25rem); }
.article .kicker {
  font-family: var(--mono); font-size: 0.7rem; letter-spacing: 0.16em;
  text-transform: uppercase; color: var(--muted); margin-bottom: 1rem;
  display: flex; gap: 1rem; flex-wrap: wrap;
}
.article h1 {
  font-weight: 300; font-size: clamp(2rem, 1.4rem + 3.4vw, 3.4rem);
  line-height: 1.05; letter-spacing: -0.02em; margin: 0 0 1rem;
}
.article h1 em { font-style: italic; }
.article .byline { color: var(--ink-soft); font-style: italic; }

.prose { max-width: var(--measure); }
.prose > * { margin-inline: auto; }
.prose p { margin: 0 0 1.35rem; }
.prose h2 {
  font-weight: 400; font-size: 1.6rem; letter-spacing: -0.01em;
  margin: 2.75rem 0 1rem; line-height: 1.2;
}
.prose h2 .num { font-family: var(--mono); font-size: 0.85rem; color: var(--muted); margin-right: 0.6rem; letter-spacing: 0; }
.prose a { border-bottom: 1px solid var(--hair); transition: border-color var(--t); }
.prose a:hover { border-color: var(--ink); }
.prose blockquote {
  margin: 1.75rem 0; padding-left: 1.25rem; border-left: 2px solid var(--ink);
  font-style: italic; color: var(--ink-soft);
}
.prose code {
  font-family: var(--mono); font-size: 0.86em;
  background: var(--bg-2); padding: 0.1em 0.35em; border-radius: 2px;
}
.drop::first-letter {
  font-size: 3.4em; line-height: 0.78; float: left;
  padding: 0.08em 0.12em 0 0; font-weight: 300;
}

/* figures (full reading width, can break out a touch) */
figure.fig {
  max-width: var(--wide); margin: 2.5rem auto;
  border: 1px solid var(--hair); background: var(--bg);
}
figure.fig canvas { display: block; width: 100%; height: auto; }
figure.fig figcaption {
  font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.04em;
  color: var(--muted); padding: 0.7rem 1rem; border-top: 1px solid var(--hair);
  display: flex; gap: 0.9rem; align-items: baseline; flex-wrap: wrap;
}
figure.fig figcaption .fnum { color: var(--ink); }
.fig-controls { display: flex; gap: 0.5rem; margin-left: auto; }
.fig-controls button {
  font-family: var(--mono); font-size: 0.7rem; letter-spacing: 0.06em;
  color: var(--ink-soft); background: none; border: 1px solid var(--hair);
  padding: 0.2rem 0.6rem; cursor: pointer; transition: all var(--t);
}
.fig-controls button:hover { color: var(--bg); background: var(--ink); border-color: var(--ink); }

/* katex display blocks */
.katex-display { margin: 1.6rem 0 !important; overflow-x: auto; overflow-y: hidden; padding: 0.2rem 0; }

/* ---------- about ---------- */
.about { padding: clamp(2.5rem, 7vw, 4.5rem) 0 6rem; }
.about .prose { max-width: var(--measure); }

/* ---------- footer ---------- */
.foot {
  border-top: 1px solid var(--hair); padding: 2rem 0 3rem;
  display: flex; justify-content: space-between; align-items: baseline;
  gap: 1rem; flex-wrap: wrap;
  font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.06em;
  color: var(--muted);
}
.foot a { border-bottom: 1px solid transparent; transition: border-color var(--t), color var(--t); }
.foot a:hover { color: var(--ink); border-color: var(--ink); }

/* ---------- mobile ---------- */
@media (max-width: 640px) {
  .nav { gap: 1.1rem; }
  .entry { grid-template-columns: 1fr; gap: 0.3rem; }
  .entry .e-date { grid-column: 1; grid-row: 1; order: -1; padding-top: 0; }
  .entry .e-tags { grid-column: 1; justify-self: start; }
  .entry:hover { padding-left: 0.6rem; }
}

@media (prefers-reduced-motion: reduce) {
  * { animation-duration: 0.001ms !important; transition-duration: 0.001ms !important; }
}