/* ============================================================
   Commonweave — Brand System
   Tokens, base styles, layout primitives.
   ============================================================ */

:root {
  /* --- Color: botanical, ink, paper -------------------------- */
  --paper:        #F2EBDC;   /* cream, primary surface */
  --paper-2:      #E9DFC9;   /* deeper cream */
  --paper-3:      #DCD0B6;   /* card / inset */
  --ink:          #16201A;   /* near-black ink, slightly green */
  --ink-soft:     #2C3A30;
  --ink-muted:    #5A6A5C;

  --moss:         #2F4A33;   /* deep green — primary brand */
  --moss-deep:    #1E3322;
  --moss-mid:     #4A6B4F;
  --moss-pale:    #B8C4A8;

  --clay:         #B4593A;   /* warm accent — single, used sparingly */
  --clay-pale:    #D9A78F;

  --thread:       #8E7B4E;   /* linen thread — secondary accent */
  --thread-pale:  #C9B98C;

  /* --- Type ---------------------------------------------------- */
  --f-display: "Instrument Serif", "Source Serif 4", Georgia, serif;
  --f-body:    "Source Serif 4", "Iowan Old Style", Georgia, serif;
  --f-mono:    "JetBrains Mono", ui-monospace, "SF Mono", monospace;

  /* --- Scale --------------------------------------------------- */
  --s-1: 4px;
  --s-2: 8px;
  --s-3: 12px;
  --s-4: 16px;
  --s-5: 24px;
  --s-6: 32px;
  --s-7: 48px;
  --s-8: 72px;
  --s-9: 112px;
  --s-10: 160px;

  /* --- Misc ---------------------------------------------------- */
  --rule: 1px solid var(--ink);
  --rule-soft: 1px solid color-mix(in oklab, var(--ink) 25%, transparent);
  --rule-hair: 0.5px solid color-mix(in oklab, var(--ink) 40%, transparent);
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--f-body);
  font-size: 17px;
  line-height: 1.55;
  font-feature-settings: "ss01", "onum";
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* Subtle paper grain — radial speckle layered with gradient warmth */
body {
  background:
    radial-gradient(800px 600px at 80% -10%, color-mix(in oklab, var(--thread-pale) 30%, transparent), transparent 60%),
    radial-gradient(700px 500px at -5% 110%, color-mix(in oklab, var(--moss-pale) 25%, transparent), transparent 65%),
    var(--paper);
}

::selection { background: var(--moss); color: var(--paper); }

/* ===== Typography primitives ===== */
.display {
  font-family: var(--f-display);
  font-weight: 400;
  letter-spacing: -0.015em;
  line-height: 0.95;
  font-style: italic;
}
.eyebrow {
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--ink-muted);
  font-weight: 500;
}
.lede {
  font-family: var(--f-display);
  font-size: clamp(28px, 3.4vw, 44px);
  line-height: 1.1;
  letter-spacing: -0.01em;
  font-weight: 400;
}
.kicker {
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}
h1, h2, h3, h4 {
  font-family: var(--f-display);
  font-weight: 400;
  letter-spacing: -0.01em;
  margin: 0;
}
h2 { font-size: clamp(40px, 5vw, 72px); line-height: 1; font-style: italic; }
h3 { font-size: clamp(22px, 2vw, 28px); line-height: 1.15; }
p  { margin: 0 0 1em; max-width: 62ch; text-wrap: pretty; }
em { font-style: italic; color: var(--moss-deep); }

/* ===== Layout ===== */
.app {
  display: grid;
  grid-template-columns: 280px 1fr;
  min-height: 100vh;
}

aside.nav {
  position: sticky;
  top: 0;
  height: 100vh;
  border-right: var(--rule);
  padding: var(--s-7) var(--s-6);
  background:
    linear-gradient(180deg, var(--paper) 0%, var(--paper-2) 100%);
  display: flex;
  flex-direction: column;
  gap: var(--s-7);
  overflow-y: auto;
}
aside.nav .brand {
  display: flex;
  flex-direction: column;
  gap: var(--s-2);
}
aside.nav .brand .mark {
  font-family: var(--f-display);
  font-style: italic;
  font-size: 28px;
  letter-spacing: -0.02em;
}
aside.nav .brand .meta {
  font-family: var(--f-mono);
  font-size: 10px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-muted);
}
aside.nav nav ol {
  list-style: none;
  padding: 0;
  margin: 0;
  counter-reset: section;
  display: flex;
  flex-direction: column;
  gap: var(--s-1);
}
aside.nav nav li {
  counter-increment: section;
}
aside.nav nav a {
  display: grid;
  grid-template-columns: 28px 1fr;
  align-items: baseline;
  gap: var(--s-3);
  text-decoration: none;
  color: var(--ink);
  padding: 8px 0;
  font-size: 14px;
  line-height: 1.35;
  border-bottom: var(--rule-hair);
  transition: color .2s ease, padding .2s ease;
}
aside.nav nav a::before {
  content: counter(section, decimal-leading-zero);
  font-family: var(--f-mono);
  font-size: 10px;
  letter-spacing: 0.1em;
  color: var(--ink-muted);
}
aside.nav nav a:hover {
  color: var(--moss);
  padding-left: 4px;
}
aside.nav nav a.is-active {
  color: var(--moss-deep);
  font-style: italic;
}
aside.nav .footer {
  margin-top: auto;
  font-family: var(--f-mono);
  font-size: 10px;
  letter-spacing: 0.1em;
  color: var(--ink-muted);
  line-height: 1.7;
}

main.content {
  padding: 0;
}

/* ===== Section frames ===== */
section.section {
  padding: var(--s-9) clamp(40px, 6vw, 96px);
  border-bottom: var(--rule);
  position: relative;
}
section.section + section.section { /* alternate paper */ }
section.section.alt { background: color-mix(in oklab, var(--paper-2) 75%, var(--paper)); }
section.section.dark {
  background: var(--ink);
  color: var(--paper);
}
section.section.dark .eyebrow { color: var(--thread-pale); }
section.section.dark em { color: var(--moss-pale); }

.section-head {
  display: grid;
  grid-template-columns: 120px 1fr;
  gap: var(--s-6);
  align-items: baseline;
  margin-bottom: var(--s-8);
}
.section-head .num {
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--ink-muted);
  text-transform: uppercase;
}
.section-head h2 {
  max-width: 18ch;
}
.section-head .blurb {
  grid-column: 2;
  font-family: var(--f-body);
  font-size: 18px;
  color: var(--ink-soft);
  max-width: 64ch;
  margin-top: var(--s-5);
}

/* ===== Cards / chips ===== */
.card {
  background: var(--paper);
  border: var(--rule);
  padding: var(--s-6);
}
.card.inset { background: var(--paper-3); }

.chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--f-mono);
  font-size: 10px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  padding: 4px 10px;
  border: 1px solid currentColor;
  border-radius: 999px;
  color: var(--ink-muted);
}

/* ===== Marginalia (Feynman-flavor side note) ===== */
.marginalia {
  font-family: var(--f-mono);
  font-size: 11px;
  line-height: 1.5;
  color: var(--ink-muted);
  letter-spacing: 0.02em;
  border-left: 2px solid var(--moss);
  padding-left: var(--s-4);
  max-width: 28ch;
}

/* ===== Two-up grid ===== */
.two-up { display: grid; grid-template-columns: 1fr 1fr; gap: var(--s-7); }
.three-up { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--s-6); }
.four-up { display: grid; grid-template-columns: repeat(4, 1fr); gap: var(--s-4); }
@media (max-width: 900px) {
  .two-up, .three-up, .four-up { grid-template-columns: 1fr; }
}

/* ===== Reveal on scroll ===== */
.reveal {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity .9s cubic-bezier(.2,.6,.1,1), transform .9s cubic-bezier(.2,.6,.1,1);
}
.reveal.in { opacity: 1; transform: none; }

/* ===== Utility ===== */
.rule { border-top: var(--rule); margin: var(--s-7) 0; }
.rule.soft { border-top: var(--rule-soft); }
.tabular { font-variant-numeric: tabular-nums; }

/* ===== Mobile ===== */
@media (max-width: 900px) {
  .app { grid-template-columns: 1fr; }
  aside.nav {
    position: static;
    height: auto;
    border-right: 0;
    border-bottom: var(--rule);
  }
  .section-head { grid-template-columns: 1fr; }
  .section-head .blurb { grid-column: 1; }
}