/* RAMS/ — design system.
   Law: warm paper, ink, one accent for interactive truth, 4/8px spacing,
   hairlines instead of shadows, 160ms ease-out, nothing decorative.
   One page, read top to bottom: overture → objects → principles → colophon. */

/* Tokens */
:root {
  --paper: #fafaf8;
  --paper-step: #f0efea;
  --ink: #1c1b18;
  --ink-2: #6e6c64;
  --hairline: #dddbd2;
  --accent: #e8500f;
  --accent-press: #b53d08;

  --s1: 4px; --s2: 8px; --s3: 12px; --s4: 16px; --s5: 24px;
  --s6: 32px; --s7: 48px; --s8: 64px; --s9: 96px; --s10: 128px;

  /* Modular scale, ratio 1.25 from 16 */
  --t-1: 0.8125rem;   /* 13 */
  --t0: 1rem;         /* 16 */
  --t1: 1.25rem;      /* 20 */
  --t2: 1.5625rem;    /* 25 */
  --t3: 1.9531rem;    /* 31 */
  --t4: 2.4414rem;    /* 39 */
  --t5: 3.0518rem;    /* 49 */
  --t6: 3.8147rem;    /* 61 */
  --t7: 4.7684rem;    /* 76 */
  --t8: 5.9605rem;    /* 95 */

  --ease: cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

/* Reset */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}

body {
  background: var(--paper);
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  color: var(--ink);
  font-family: "Helvetica Neue", Helvetica, Arial, system-ui, sans-serif;
  font-size: var(--t0);
  line-height: 1.5;
  font-kerning: normal;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

img, svg, canvas { display: block; max-width: 100%; }

a { color: inherit; text-decoration: none; }
.fallback-svg[hidden] { display: none; }

[id] { scroll-margin-top: 72px; } /* clear the sticky header on anchor jumps */

/* Focus: visible, exact, everywhere */
:focus { outline: none; }
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 1px;
}

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

/* Layout shell */
.shell {
  max-width: 1128px;
  margin-inline: auto;
  padding-inline: var(--s5);
}

.rule { border: 0; border-top: 1px solid var(--hairline); }

.sr-only {
  position: absolute;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}

/* Reading line: honest progress along the journey */
#progress {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: 2px;
  background: var(--accent);
  transform-origin: 0 50%;
  transform: scaleX(0);
  z-index: 20;
  pointer-events: none;
}

/* Header */
.site-head {
  position: sticky; top: 0; z-index: 10;
  background: color-mix(in srgb, var(--paper) 92%, transparent);
  backdrop-filter: blur(6px);
  border-bottom: 1px solid var(--hairline);
}
.site-head .shell {
  display: flex; align-items: baseline; justify-content: space-between;
  padding-block: var(--s4);
}
.wordmark {
  font-size: var(--t1);
  font-weight: 700;
  letter-spacing: 0.02em;
}
.wordmark .slash { color: var(--accent); }
.site-nav { display: flex; gap: var(--s5); font-size: var(--t-1); letter-spacing: 0.06em; text-transform: uppercase; }
.site-nav a {
  padding-block: var(--s1);
  color: var(--ink-2);
  transition: color 160ms var(--ease);
}
.site-nav a:hover { color: var(--ink); }

/* Footer */
main { flex: 1; }

.site-foot {
  margin-top: var(--s9);
  border-top: 1px solid var(--hairline);
  padding-block: var(--s6) var(--s7);
  color: var(--ink-2);
  font-size: var(--t-1);
}
.site-foot .shell {
  display: flex; flex-wrap: wrap; gap: var(--s4) var(--s7); justify-content: space-between;
}
.site-foot a { color: var(--ink); }
.site-foot a:hover { color: var(--accent-press); }

/* Type utilities */
.display {
  font-weight: 700;
  line-height: 1.02;
  letter-spacing: -0.015em;
  text-wrap: balance;
}
.measure { max-width: 62ch; }
.muted { color: var(--ink-2); }
.num { font-variant-numeric: tabular-nums; }

/* Links inside prose and lists */
.prose a, .link {
  color: var(--ink);
  border-bottom: 1px solid var(--accent);
  transition: color 160ms var(--ease), border-color 160ms var(--ease);
}
.prose a:hover, .link:hover { color: var(--accent-press); }

/* Buttons: pressable things may carry honest dimensionality */
.button {
  display: inline-block;
  font: inherit;
  font-size: var(--t-1);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink);
  background: var(--paper);
  border: 1px solid var(--ink);
  border-radius: 2px;
  padding: var(--s3) var(--s5);
  box-shadow: 0 1px 0 rgba(28, 27, 24, 0.25); /* outset = genuinely pressable */
  cursor: pointer;
  transition: background-color 160ms var(--ease),
              color 160ms var(--ease),
              box-shadow 160ms var(--ease),
              transform 160ms var(--ease);
}
.button:hover { background: var(--ink); color: var(--paper); }
.button:active {
  transform: translateY(1px);
  box-shadow: inset 0 1px 2px rgba(28, 27, 24, 0.35); /* inset = pressed is real */
}

/* Scroll reveals: one 160ms arrival, only when JS is present to reveal */
.js .rv {
  opacity: 0;
  translate: 0 12px;
}
.js .rv[data-visible] {
  opacity: 1;
  translate: 0 0;
  transition: opacity 160ms var(--ease), translate 160ms var(--ease);
}

/* Overture */
.hero { padding-block: var(--s10) var(--s8); }
.hero h1 {
  font-size: clamp(var(--t6), 9vw, var(--t8));
  max-width: 12ch;
}
.hero .lede {
  margin-top: var(--s6);
  font-size: var(--t2);
  line-height: 1.35;
  max-width: 38ch;
  color: var(--ink);
}
.hero .lede .muted { color: var(--ink-2); }

.strip { padding-block: var(--s8) 0; }
.strip .prose { color: var(--ink-2); }

/* Act heads: Roman-numeral chapters of the document */
.act {
  position: relative;
  padding-block: var(--s10) var(--s6);
}
.act::before {
  content: attr(data-num);
  position: absolute;
  top: var(--s7);
  right: 0;
  font-size: clamp(var(--t7), 14vw, var(--t8));
  font-weight: 700;
  line-height: 0.9;
  color: var(--paper-step);
  -webkit-text-stroke: 1px var(--hairline);
  user-select: none;
}
.act h2 { font-size: clamp(var(--t4), 5vw, var(--t6)); }
.act .sub {
  margin-top: var(--s4);
  font-size: var(--t1);
  color: var(--ink-2);
  max-width: 52ch;
}

/* Object spreads: drawing left, facts right, mirrored in alternation */
.spread {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
  gap: var(--s7);
  align-items: center;
  padding-block: var(--s9) var(--s8);
  border-top: 1px solid var(--hairline);
}
.spread::before {
  content: attr(data-no);
  position: absolute;
  top: var(--s4);
  right: 0;
  font-size: var(--t6);
  font-weight: 700;
  line-height: 1;
  color: var(--paper-step);
  -webkit-text-stroke: 1px var(--hairline);
  font-variant-numeric: tabular-nums;
  user-select: none;
}
.spread:nth-of-type(even) .spread-art { order: 2; }
.spread .study-frame { aspect-ratio: 1 / 1; } /* monumental: the drawing is the imagery */
.spread-meta h3 {
  font-size: clamp(var(--t4), 6vw, var(--t5));
  line-height: 1;
}
.spread-meta .essence {
  margin-top: var(--s4);
  font-size: var(--t2);
  max-width: 30ch;
  color: var(--ink);
}
.spec-mini { margin-top: var(--s5); }
.carries {
  margin-top: var(--s5);
  font-size: var(--t-1);
  letter-spacing: 0.04em;
  color: var(--ink-2);
}
.carries a {
  color: var(--accent-press);
  border-bottom: 1px solid var(--accent);
  padding-bottom: 1px;
  transition: color 160ms var(--ease), border-color 160ms var(--ease);
}
.carries a:hover { color: var(--ink); border-color: var(--ink); }

.ten {
  position: relative;
  max-width: 62ch;
  margin-inline: auto;
  padding-inline: var(--s5);
  padding-block: var(--s9);
  border-top: 1px solid var(--hairline);
}
.ten::before {
  content: attr(data-num);
  display: block;
  font-variant-numeric: tabular-nums;
  font-size: clamp(var(--t7), 14vw, var(--t8));
  font-weight: 700;
  line-height: 0.9;
  color: var(--paper-step);
  -webkit-text-stroke: 1px var(--hairline);
  user-select: none;
}
.ten h3 {
  font-size: clamp(var(--t4), 5vw, var(--t6));
  margin-top: calc(-0.45 * var(--t6));
}
.statement {
  margin-top: var(--s6);
  padding-left: var(--s5);
  border-left: 2px solid var(--accent);
  font-size: var(--t2);
  line-height: 1.4;
  max-width: 46ch;
}
.proof-row {
  list-style: none;
  margin-top: var(--s6);
  display: grid;
  gap: var(--s3);
}
.proof-row li a {
  display: grid;
  grid-template-columns: minmax(4rem, 6rem) 1fr;
  gap: var(--s4);
  align-items: baseline;
}
.proof-row .model { font-weight: 700; font-variant-numeric: tabular-nums; transition: color 160ms var(--ease); }
.proof-row a:hover .model { color: var(--accent-press); }
.proof-row .why { color: var(--ink-2); font-size: var(--t-1); }

/* Prose */
.prose { margin-top: var(--s6); }
.prose p + p { margin-top: var(--s4); }
.prose p { max-width: 62ch; }

.section-label {
  margin-top: var(--s8);
  padding-bottom: var(--s2);
  border-bottom: 1px solid var(--hairline);
  font-size: var(--t-1);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-2);
}

/* Object study (canvas + fallback svg) */
.study {
  margin-block: var(--s8) var(--s9);
  border-block: 1px solid var(--hairline);
  padding-block: var(--s6);
}
.study-frame { position: relative; aspect-ratio: 16 / 10; }
.study-frame canvas { position: absolute; inset: 0; width: 100%; height: 100%; cursor: grab; touch-action: pan-y; }
.study-frame canvas:active { cursor: grabbing; }
.study-frame canvas:focus-visible { outline-offset: -2px; }
.study-frame canvas[hidden] { display: none; }
.study-caption {
  display: flex; justify-content: space-between; gap: var(--s4);
  padding-top: var(--s4); font-size: var(--t-1); color: var(--ink-2);
}
.fallback-svg { width: 100%; height: 100%; }
.fallback-svg path, .fallback-svg rect, .fallback-svg circle, .fallback-svg line, .fallback-svg ellipse {
  fill: none; stroke: var(--ink); stroke-width: 1.25;
}

/* Specification tables */
.spec-table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--t0);
  font-variant-numeric: tabular-nums;
  max-width: 34rem;
}
.spec-table caption {
  text-align: left;
  padding-bottom: var(--s2);
  font-size: var(--t-1); letter-spacing: 0.08em; text-transform: uppercase; color: var(--ink-2);
}
.spec-table th, .spec-table td {
  text-align: left;
  padding: var(--s2) 0;
  border-bottom: 1px solid var(--hairline);
  vertical-align: top;
}
.spec-table th { font-weight: 400; color: var(--ink-2); width: 9rem; }

/* Colophon table */
.byte-table {
  width: 100%; border-collapse: collapse; max-width: 40rem;
  font-variant-numeric: tabular-nums;
}
.byte-table th, .byte-table td {
  text-align: left; padding: var(--s2) 0;
  border-bottom: 1px solid var(--hairline); font-size: var(--t-1);
}
.byte-table th:last-child, .byte-table td:last-child { text-align: right; white-space: nowrap; }
.byte-table td code { overflow-wrap: anywhere; }
.byte-total td { font-weight: 700; border-bottom: none; padding-top: var(--s3); }
.colo { padding-bottom: var(--s6); }

/* 404 */
.lost { padding-block: var(--s10) var(--s9); }
.lost h1 { font-size: var(--t8); line-height: 1; }
.lost p { margin-top: var(--s4); font-size: var(--t2); max-width: 30ch; }

/* Object study + working object, side by side */
.study-duo {
  display: grid;
  grid-template-columns: minmax(0, 7fr) minmax(280px, 5fr);
  gap: var(--s7);
  align-items: center;
}
.study-duo > div { width: 100%; }
@media (max-width: 880px) {
  .study-duo { grid-template-columns: 1fr; }
  .et66-wrap { max-width: 340px; }
}

/* ET66 working calculator — the one dimensional object.
   Keys are real controls: outset at rest, inset when pressed. */
.et66 {
  width: min(340px, 100%);
  background: var(--paper-step);
  border: 1px solid var(--hairline);
  border-radius: 12px;
  padding: var(--s4);
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.8),
    0 1px 2px rgba(28, 27, 24, 0.08);
}
.et66-display {
  font-variant-numeric: tabular-nums;
  font-size: var(--t3);
  text-align: right;
  color: var(--paper);
  background: var(--ink);
  border-radius: 6px;
  padding: var(--s3) var(--s4);
  margin-bottom: var(--s4);
  min-height: 3.25rem;
  display: flex;
  align-items: center;
  justify-content: flex-end;
  box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.45);
  overflow: hidden;
}
.et66-keys {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--s2);
}
.et66-keys button {
  font: inherit;
  font-size: var(--t1);
  font-variant-numeric: tabular-nums;
  color: var(--ink);
  background: var(--paper);
  border: 1px solid var(--hairline);
  border-radius: 8px;
  padding: var(--s3) 0;
  cursor: pointer;
  box-shadow: 0 2px 0 rgba(28, 27, 24, 0.18);
  transition: transform 160ms var(--ease), box-shadow 160ms var(--ease),
              background-color 160ms var(--ease);
}
.et66-keys button:hover { background: #ffffff; }
.et66-keys button:active {
  transform: translateY(2px);
  box-shadow: inset 0 1px 3px rgba(28, 27, 24, 0.35);
}
.et66-keys .fn { color: var(--ink-2); }
.et66-keys .op { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.et66-keys .op:hover { background: #000; }
.et66-keys .eq { background: var(--accent-press); color: #fff; border-color: #8f3006; }
.et66-keys .eq:hover { background: #8f3006; }

/* Responsive */
@media (max-width: 880px) {
  .spread { grid-template-columns: 1fr; gap: var(--s5); padding-block: var(--s7); }
  .spread:nth-of-type(even) .spread-art { order: 0; }
}
@media (max-width: 720px) {
  .hero { padding-block: var(--s7); }
  .act { padding-block: var(--s8) var(--s5); }
  .ten h3 { margin-top: calc(-0.35 * var(--t6)); }
  .statement { padding-left: var(--s4); }
  .site-head .shell { flex-direction: column; gap: var(--s2); align-items: flex-start; }
  .site-nav { gap: var(--s4); }
  [id] { scroll-margin-top: 104px; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  .js .rv { opacity: 1; translate: none; }
}