/* in-optimizer — laboratory instrument */

:root {
  /* palette */
  --ink: #0F1116;
  --surface: #15171F;
  --hairline: #2A2D38;
  --paper: #E8E5DC;
  --paper-dim: #A8A39A;
  --brass: #C9A227;
  --terra: #D14A3D;

  /* type */
  --display: 'Instrument Serif', Georgia, 'Times New Roman', serif;
  --sans: 'IBM Plex Sans', -apple-system, BlinkMacSystemFont, sans-serif;
  --mono: 'IBM Plex Mono', 'JetBrains Mono', ui-monospace, Menlo, monospace;

  /* scale (mobile defaults) */
  --fs-mono: 13px;
  --fs-body: 16px;
  --fs-lead: 18px;
  --fs-h3: 22px;
  --fs-h2: 28px;
  --fs-h1: 44px;

  /* layout */
  --gutter: 20px;
  --max-content: 1040px;
  --max-text: 65ch;
  --tick: 60px;
}

@media (min-width: 640px) {
  :root { --gutter: 32px; --fs-h1: 52px; }
}
@media (min-width: 1024px) {
  :root {
    --fs-mono: 14px; --fs-body: 17px; --fs-lead: 20px;
    --fs-h3: 26px; --fs-h2: 36px; --fs-h1: 72px;
  }
}

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

html { scroll-behavior: smooth; }

body {
  background: var(--ink);
  color: var(--paper);
  font-family: var(--sans);
  font-size: var(--fs-body);
  line-height: 1.55;
  font-feature-settings: 'kern' 1, 'liga' 1;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* layout */
.frame {
  max-width: var(--max-content);
  margin: 0 auto;
  padding: 0 var(--gutter);
}

main { padding: 64px 0 96px; }

@media (min-width: 1024px) {
  main { padding: 112px 0 144px; }
}

/* nav (sparse) */
.nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 24px 0;
  font-family: var(--mono);
  font-size: var(--fs-mono);
  color: var(--paper-dim);
  letter-spacing: 0.04em;
}
.nav a { color: var(--paper-dim); text-decoration: none; }
.nav a:hover { color: var(--brass); }
.lang-switch { border-bottom: 1px solid var(--hairline); padding-bottom: 2px; }

.wordmark {
  font-family: var(--display);
  font-style: italic;
  font-weight: 400;
  font-size: 24px;
  color: var(--paper);
  text-decoration: none;
  letter-spacing: -0.01em;
}
.wordmark::before {
  content: '';
  display: inline-block;
  width: 14px;
  height: 14px;
  margin-right: 8px;
  background: url('favicon.svg') center/contain no-repeat;
  vertical-align: -2px;
}

/* hero */
.hero { padding: 56px 0 80px; }
@media (min-width: 1024px) {
  .hero {
    padding: 96px 0 144px;
    display: grid;
    grid-template-columns: 5fr 7fr;
    gap: 64px;
    align-items: end;
  }
}

.hero h1 {
  font-family: var(--display);
  font-weight: 400;
  font-size: var(--fs-h1);
  line-height: 1.05;
  letter-spacing: -0.02em;
  color: var(--paper);
  margin-bottom: 24px;
}
.hero h1 em {
  font-style: italic;
  color: var(--brass);
}
.hero p.lead {
  font-size: var(--fs-lead);
  color: var(--paper-dim);
  max-width: 36ch;
  line-height: 1.5;
}

/* pace clock + readout */
.instrument {
  margin-top: 56px;
  padding-top: 32px;
  border-top: 1px solid var(--hairline);
}
@media (min-width: 1024px) {
  .instrument { margin-top: 0; padding-top: 0; border-top: none; }
}
.pace-clock {
  width: 100%;
  height: 24px;
  display: block;
  animation: breath 10s ease-in-out infinite;
}
@keyframes breath {
  0%, 100% { opacity: 0.55; }
  50%      { opacity: 0.95; }
}
.readout {
  margin-top: 28px;
  font-family: var(--mono);
  font-size: var(--fs-mono);
  line-height: 1.85;
  color: var(--paper-dim);
}
.readout dt {
  display: inline-block;
  width: 9ch;
  color: var(--paper-dim);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  font-weight: 500;
}
.readout dd { display: inline; color: var(--paper); }
.readout dd::after { content: '\A'; white-space: pre; }

/* section heading with brass tally */
section { padding: 56px 0; }
@media (min-width: 1024px) { section { padding: 96px 0; } }
section h2 {
  font-family: var(--display);
  font-weight: 400;
  font-style: italic;
  font-size: var(--fs-h2);
  letter-spacing: -0.015em;
  color: var(--paper);
  margin-bottom: 24px;
  position: relative;
  padding-top: 20px;
}
section h2::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: var(--tick);
  height: 1px;
  background: var(--brass);
}
[dir="rtl"] section h2::before { left: auto; right: 0; }

section p, section li {
  font-size: var(--fs-body);
  color: var(--paper);
  max-width: var(--max-text);
}
section p + p, section p + ul, section ul + p { margin-top: 16px; }

/* lists */
.bare { list-style: none; }
.bare li {
  padding: 12px 0;
  border-bottom: 1px solid var(--hairline);
}
.bare li:last-child { border-bottom: none; }
.bare li::before {
  content: '';
  display: inline-block;
  width: 18px;
  height: 1px;
  background: var(--paper-dim);
  vertical-align: middle;
  margin-right: 12px;
  margin-bottom: 4px;
}
[dir="rtl"] .bare li::before { margin-right: 0; margin-left: 12px; }
.does-not .bare li::before { background: var(--terra); }

.does-not h2::before { background: var(--terra); }
.does-not .eyebrow { color: var(--terra); }
.eyebrow {
  font-family: var(--mono);
  font-size: var(--fs-mono);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--paper-dim);
  margin-bottom: 12px;
}

/* roman-numeral chapters */
.steps { display: grid; gap: 40px; }
.step { display: grid; grid-template-columns: 60px 1fr; gap: 16px; align-items: baseline; }
[dir="rtl"] .step { grid-template-columns: 1fr 60px; }
.step .num {
  font-family: var(--display);
  font-style: italic;
  font-size: 32px;
  color: var(--brass);
  line-height: 1;
}
.step h3 {
  font-family: var(--sans);
  font-weight: 600;
  font-size: var(--fs-h3);
  margin-bottom: 8px;
}
.step p { color: var(--paper-dim); }
.step code, .step kbd {
  font-family: var(--mono);
  font-size: 0.92em;
  color: var(--brass);
  background: var(--surface);
  padding: 1px 6px;
  border-radius: 3px;
}

/* code block */
pre.code {
  background: var(--surface);
  border: 1px solid var(--hairline);
  padding: 20px 24px;
  font-family: var(--mono);
  font-size: var(--fs-mono);
  color: var(--paper);
  overflow-x: auto;
  line-height: 1.7;
  margin: 24px 0;
}
pre.code .comment { color: var(--paper-dim); }
pre.code .accent  { color: var(--brass); }

/* architecture tree */
.tree {
  font-family: var(--mono);
  font-size: var(--fs-mono);
  background: var(--surface);
  border: 1px solid var(--hairline);
  padding: 20px 24px;
  margin: 24px 0;
  white-space: pre;
  overflow-x: auto;
  line-height: 1.7;
}
.tree .file { color: var(--paper); }
.tree .desc { color: var(--paper-dim); }
.tree .arrow { color: var(--brass); }

/* links */
a { color: var(--paper); text-decoration: underline; text-decoration-color: var(--brass); text-underline-offset: 3px; text-decoration-thickness: 1px; }
a:hover { color: var(--brass); }

/* author */
.author { display: flex; flex-direction: column; gap: 4px; }
.author .name {
  font-family: var(--display);
  font-style: italic;
  font-size: 28px;
  color: var(--paper);
}
.author .meta {
  font-family: var(--mono);
  font-size: var(--fs-mono);
  color: var(--paper-dim);
  letter-spacing: 0.04em;
}

/* footer */
footer {
  border-top: 1px solid var(--hairline);
  margin-top: 96px;
  padding: 32px 0;
  font-family: var(--mono);
  font-size: var(--fs-mono);
  color: var(--paper-dim);
  letter-spacing: 0.04em;
  text-align: center;
}
footer a { color: var(--paper-dim); }
footer a:hover { color: var(--brass); }

/* entrance: one staggered reveal on first paint */
.hero h1, .hero p.lead, .instrument {
  opacity: 0;
  animation: rise 700ms ease-out forwards;
}
.hero h1     { animation-delay: 80ms; }
.hero p.lead { animation-delay: 240ms; }
.instrument  { animation-delay: 420ms; }
@keyframes rise {
  from { opacity: 0; transform: translateY(12px); }
  to   { opacity: 1; transform: translateY(0); }
}

@media (prefers-reduced-motion: reduce) {
  .hero h1, .hero p.lead, .instrument { animation: none; opacity: 1; transform: none; }
  .pace-clock { animation: none; opacity: 0.85; }
}

/* RTL overrides — Persian page */
[dir="rtl"] {
  --display: 'Vazirmatn', 'Instrument Serif', serif;
  --sans:    'Vazirmatn', system-ui, sans-serif;
}
[dir="rtl"] .hero h1 em { font-style: normal; }
[dir="rtl"] .wordmark::before { margin-right: 0; margin-left: 8px; }
[dir="rtl"] .readout dd::after { content: '\A'; white-space: pre; }