/* The landing page. Tokens, top bar and controls are in base.css; the system is
   described in ../DESIGN.md. Three phases, one material:
     written  = solid ink, 2px solid bars, instant changes
     learned  = halftone (the --dots pattern), superposed values (--u), easing
     training = --signal, and only while an optimizer is running */

:root {
  --dots: radial-gradient(circle at center, rgb(var(--learn-rgb)) 0 .9px, transparent 1.25px);
  --dots-size: 4px 4px;
  --code-size: 14px;
}
@media (max-width: 640px) { :root { --code-size: 12.5px; } }

/* ---- Phases ------------------------------------------------------------------ */

/* Liquid type: the same glyphs, smeared into a superposition by --u (0 = solid). */
.phase {
  color: rgb(var(--ink-rgb) / calc(1 - var(--u) * .6));
  text-shadow:
    calc(var(--u) * .075em) calc(var(--u) * -.018em) calc(var(--u) * .012em) rgb(var(--learn-rgb) / calc(var(--u) * .62)),
    calc(var(--u) * -.085em) calc(var(--u) * .03em) calc(var(--u) * .02em) rgb(var(--ghost-rgb) / calc(var(--u) * .5)),
    calc(var(--u) * .03em) calc(var(--u) * .07em) calc(var(--u) * .05em) rgb(var(--ink-rgb) / calc(var(--u) * .22)),
    0 0 calc(var(--u) * .08em) rgb(var(--ink-rgb) / calc(var(--u) * .25));
  transition: --u .64s var(--ease-liquid);
}
.halftone { background-image: var(--dots); background-size: var(--dots-size); }

/* ---- Type -------------------------------------------------------------------- */
.label {
  margin: 0 0 22px; font: 500 12px/1.2 var(--mono); letter-spacing: .08em; text-transform: uppercase; color: var(--learn);
}
.h2 {
  margin: 0 0 28px; font-family: var(--display); font-weight: 800; font-variation-settings: "wdth" 115;
  font-size: clamp(34px, 5.4vw, 76px); line-height: .92; letter-spacing: -.012em; text-transform: uppercase; text-wrap: balance;
}
.h2 code { font-family: var(--mono); font-weight: 600; text-transform: none; font-size: .86em; letter-spacing: -.04em; }
.h2.wide { max-width: 16ch; }
.split .h2 { font-size: clamp(34px, 4.3vw, 62px); }
.h3 {
  margin: 0; font-family: var(--display); font-weight: 750; font-variation-settings: "wdth" 108;
  font-size: clamp(26px, 2.6vw, 38px); line-height: 1; letter-spacing: -.01em;
}
.copy p, .lede { font-size: 19px; line-height: 1.5; color: var(--ink-2); max-width: 38ch; margin: 0 0 18px; }
.lede { max-width: 44ch; }
.thesis {
  margin: 36px 0 0 !important; padding: 2px 0 2px 18px; color: var(--ink) !important;
  font: 600 22px/1.3 var(--display) !important; font-variation-settings: "wdth" 104;
  border-left: 2px solid var(--ink);
}
#software .thesis { border-left: 0; background: var(--dots) 0 0 / 2px 4px repeat-y; }
.mini { margin: 0 0 8px; font: 500 11px/1.3 var(--mono); letter-spacing: .08em; text-transform: uppercase; color: var(--faint); }
.dim { color: var(--faint); text-transform: none; letter-spacing: 0; }
.note { margin: 14px 0 0; font: 400 13px/1.55 var(--mono); color: var(--dim); }
code { font-size: .92em; }

/* ---- Sections ------------------------------------------------------------------ */
.sec { padding: 136px 0; border-top: 1px solid var(--rule); }
@media (max-width: 760px) { .sec { padding: 88px 0; } }
.split { display: grid; grid-template-columns: minmax(0, 5fr) minmax(0, 7fr); gap: 72px; align-items: start; }
.split.mirror { grid-template-columns: minmax(0, 7fr) minmax(0, 5fr); }
.split.mirror .copy { order: 2; }
@media (max-width: 960px) {
  .split, .split.mirror { grid-template-columns: minmax(0, 1fr); gap: 40px; }
  .split.mirror .copy { order: 0; }
}
.ctl {
  border: 0; background: none; padding: 6px 4px; cursor: pointer;
  font: 500 13px/1 var(--mono); color: var(--ink);
}
.ctl:hover { background: var(--ink); color: var(--paper); }
.ctl:disabled { color: var(--faint); cursor: default; background: none; }
.count { font: 500 13px/1 var(--mono); color: var(--dim); font-variant-numeric: tabular-nums; }

/* ---- Code -------------------------------------------------------------------- */
.code {
  margin: 0; padding: 0; background: none; color: var(--ink);
  font: 400 var(--code-size)/1.72 var(--mono); tab-size: 4;
  white-space: pre; overflow-x: auto; overflow-y: hidden;
  scrollbar-width: thin;
}
.code code { font: inherit; }
/* Lines rendered by code.js: [number][phase bar] text */
.code .ln { display: block; position: relative; padding-left: 52px; min-height: 1.72em; }
.code .ln::before {
  content: attr(data-n); position: absolute; left: 0; width: 26px; text-align: right;
  color: var(--faint); opacity: .7; font-variant-numeric: tabular-nums;
}
.code .ln::after {
  content: ""; position: absolute; left: 36px; top: 0; bottom: 0; width: 2px;
}
.code .ln[data-phase="written"]::after { background: var(--ink); }
.code .ln[data-phase="learned"]::after { background: var(--dots); background-size: 2px 4px; background-repeat: repeat-y; }
.code .ln[data-phase="signal"]::after { background: var(--signal); }
.code.past { color: var(--dim); font-size: calc(var(--code-size) - 1px); }
.code.past .ln::after { opacity: .35; }
/* Tokens: typographic, not coloured. */
.code .k { font-weight: 600; }
.code .s { color: var(--ink-2); }
.code .c { color: var(--faint); font-style: italic; }
.code .n { font-variant-numeric: tabular-nums; }
.code .f { font-weight: 600; }
.code .p { color: var(--dim); }
.code .l { text-decoration: underline dotted rgb(var(--learn-rgb)); text-decoration-thickness: 1.5px; text-underline-offset: 4px; }
.code .val { color: var(--dim); }

.was, .now { margin: 0 0 10px; font: 500 11px/1.3 var(--mono); letter-spacing: .08em; text-transform: uppercase; }
.was { color: var(--faint); }
.now { margin-top: 30px; color: var(--ink); }
.hint { color: var(--faint); text-transform: none; letter-spacing: 0; }
.file { margin: 14px 0 0; font: 400 12px/1.4 var(--mono); color: var(--faint); }
.file a { color: var(--ink); }

/* ---- Hero -------------------------------------------------------------------- */
.hero { padding: clamp(40px, 7vh, 84px) 0 72px; position: relative; }
/* halftone field of the learned phase, printed behind the hero */
.hero::before { content: ""; position: absolute; top: 0; right: 0; width: 55%; height: 100%; background-image: var(--dots); background-size: 8px 8px; opacity: .55; -webkit-mask-image: radial-gradient(ellipse at 85% 30%, #000 0%, transparent 70%); mask-image: radial-gradient(ellipse at 85% 30%, #000 0%, transparent 70%); pointer-events: none; }
.hero > * { position: relative; }
.hl {
  margin: 0; font-family: var(--display); font-weight: 820; font-variation-settings: "wdth" 116;
  font-size: clamp(42px, 8.6vw, 132px); line-height: .88; letter-spacing: -.018em; text-transform: uppercase;
}
.hl-line { display: block; transition: opacity .4s ease; }
@media (min-width: 761px) {
  .hl { font-size: calc((min(100vw, var(--max)) - 2 * var(--gutter)) / 14.9); }
  .hl-line { white-space: nowrap; }
}
.hl[data-focus] .hl-line { opacity: .26; }
.hl[data-focus="program"] .hl-line[data-line="program"],
.hl[data-focus="train"] .hl-line[data-line="train"] { opacity: 1; }

.hero-run {
  display: grid; grid-template-columns: minmax(0, 1.12fr) minmax(0, 1fr); gap: 56px;
  margin-top: clamp(32px, 5vh, 56px); padding-top: 22px; border-top: 1px solid var(--ink);
}
.kicker { display: flex; gap: 22px; margin: 0 0 16px; font: 500 11px/1.2 var(--mono); letter-spacing: .08em; text-transform: uppercase; }
.kicker .step { color: var(--faint); cursor: pointer; padding: 2px 0; border: 0; border-bottom: 1px solid transparent; background: none; font: inherit; letter-spacing: inherit; text-transform: inherit; }
.kicker .step:hover { color: var(--ink); }
.kicker .step[aria-current="step"] { color: var(--ink); border-bottom-color: var(--ink); }
#hero-code { --code-size: 17px; min-height: calc(4 * 1.72em); }
@media (max-width: 640px) { #hero-code { --code-size: 12.5px; } }
.hero-meter { margin: 14px 0 0; min-height: 1.4em; font: 500 13px/1.4 var(--mono); color: var(--signal); font-variant-numeric: tabular-nums; }
.hero-meter .done { color: var(--dim); }

/* The call site: tickets in, values out. */
.io { list-style: none; margin: 0; padding: 0; font: 400 15px/1.3 var(--mono); }
.io li {
  display: grid; grid-template-columns: minmax(0, 1fr) 10.5ch; gap: 16px; align-items: center;
  padding: 13px 0; border-bottom: 1px solid var(--rule); min-height: 52px;
}
.io li:first-child { border-top: 1px solid var(--rule); }
.io q { color: var(--ink-2); quotes: "“" "”"; overflow-wrap: anywhere; }
.io output { position: relative; display: block; height: 1.3em; font-weight: 600; }
.io .wrong output { text-decoration: line-through; text-decoration-thickness: 1px; color: var(--faint); }

/* A superposed value: every label stacked, opacity = probability. */
.sup { position: relative; display: block; height: 1.3em; }
.sup span {
  position: absolute; left: 0; top: 0; white-space: nowrap;
  transition: opacity .18s linear, filter .18s linear, transform .18s linear;
}
.solid-out { font-weight: 600; }

.hero-foot {
  display: grid; grid-template-columns: minmax(0, 1.12fr) minmax(0, 1fr); gap: 56px; align-items: end;
  margin-top: 44px;
}
.hero-sub { margin: 0; font: 500 clamp(19px, 1.7vw, 23px)/1.35 var(--display); font-variation-settings: "wdth" 100; color: var(--ink-2); max-width: 34ch; }
.hero-cta { display: flex; flex-wrap: wrap; gap: 10px 12px; align-items: center; }
.install {
  display: inline-flex; align-items: center; gap: 10px; min-height: 44px; padding: 11px 16px;
  font: 500 14px/1.2 var(--mono); color: var(--paper); background: var(--ink); border: 1px solid var(--ink); cursor: copy;
}
.install .prompt { opacity: .55; }
.install .copied { font-size: 11px; opacity: .7; }
.install .copied:empty { display: none; }
.install:hover { background: transparent; color: var(--ink); }
@media (max-width: 860px) {
  .hero-run, .hero-foot { grid-template-columns: minmax(0, 1fr); gap: 28px; }
}

/* ---- Hinge ------------------------------------------------------------------ */
.hinge { padding: 120px 0 128px; background: var(--learn); color: #f7f5ef; position: relative; overflow: hidden; }
/* the hinge is printed in riso blue: paper-coloured type, with the pink plate slightly off register */
.hinge::before { content: ""; position: absolute; inset: 0; background-image: radial-gradient(circle at center, rgb(255 255 255 / .16) 0 1px, transparent 1.4px); background-size: 9px 9px; -webkit-mask-image: linear-gradient(100deg, transparent 35%, #000 100%); mask-image: linear-gradient(100deg, transparent 35%, #000 100%); pointer-events: none; }
.hinge .container { position: relative; }
.hinge .hinge-line.liquid .phase { color: #f7f5ef; text-shadow: .045em .02em 0 rgb(var(--ghost-rgb) / .85); }
.hinge-line {
  margin: 0; font-family: var(--display); font-weight: 840; font-variation-settings: "wdth" 118;
  font-size: clamp(38px, 8.2vw, 124px); line-height: .9; letter-spacing: -.018em; text-transform: uppercase;
}

/* ---- 01: demos ------------------------------------------------------------------ */
.live-note { max-width: 60ch; font-size: 17px; }
.demo { margin-top: 112px; padding-top: 22px; border-top: 1px solid var(--ink); }
.demo-head { display: grid; grid-template-columns: 10ch minmax(0, 5fr) minmax(0, 6fr); gap: 16px 32px; align-items: baseline; margin-bottom: 44px; }
.demo-head .label { margin: 0; color: var(--ink); }
.demo-head p:last-child { margin: 0; color: var(--ink-2); font-size: 17px; line-height: 1.45; max-width: 44ch; }
.demo-grid { display: grid; grid-template-columns: minmax(0, 7fr) minmax(0, 5fr); gap: 56px; align-items: start; }
@media (max-width: 1040px) {
  .demo-head { grid-template-columns: minmax(0, 1fr); gap: 10px; }
  .demo-grid { grid-template-columns: minmax(0, 1fr); gap: 40px; }
}
.demo-live { position: sticky; top: calc(var(--top-h) + 24px); }
@media (max-width: 1040px) { .demo-live { position: static; } }

/* Rules */
.rules-code .ln.rule { cursor: pointer; }
.rules-code .ln.rule:hover { background: var(--field); }
.rules-code .ln.off { color: var(--faint); }
.rules-code .ln.blocking::after { width: 5px; left: 33px; }
.rules-code .ln.blocking { font-weight: 500; }
.rules-code .ln.off::after { opacity: .25; }
.rules-code .ln .ev { position: absolute; right: 0; top: 0; font-weight: 600; font-size: .92em; }
.rules-code .ln .ev.false { color: var(--ink); }
.rules-code .ln .ev.true { color: var(--faint); }
.chips { display: flex; flex-wrap: wrap; gap: 6px; }
.chips button { border: 1px solid var(--rule-2); background: none; padding: 7px 10px; font: 400 13px/1.25 var(--mono); cursor: pointer; text-align: left; }
.chips button:hover { border-color: var(--ink); }
.chips button[aria-checked="true"] { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.state { display: grid; gap: 10px; margin: 22px 0; padding: 14px 0; border-block: 1px solid var(--rule); font: 400 13px/1.3 var(--mono); }
.state label { display: flex; align-items: center; gap: 10px; cursor: pointer; }
.state code { font-size: 1em; }
.state input[type="checkbox"] {
  -webkit-appearance: none; appearance: none; width: 16px; height: 16px; margin: 0; border: 1.5px solid var(--ink); background: none; cursor: pointer; flex: none;
}
.state input[type="checkbox"]:checked { background: var(--ink); box-shadow: inset 0 0 0 3px var(--paper); }
.state input[type="range"] { flex: 1; accent-color: var(--ink); min-width: 80px; }
.state output { width: 4ch; text-align: right; font-variant-numeric: tabular-nums; }
.options { list-style: none; margin: 0; padding: 0; }
.options li {
  display: grid; grid-template-columns: 9ch minmax(0, 1fr) 10ch; gap: 12px; align-items: center;
  padding: 10px 0 10px 12px; border-bottom: 1px solid var(--rule); font: 400 14px/1.2 var(--mono); position: relative;
}
.options li::before { content: ""; position: absolute; left: 0; top: 8px; bottom: 8px; width: 2px; }
.options li.chosen::before { background: var(--ink); }
.options li.chosen .name { font-weight: 600; }
.options .bar { height: 12px; position: relative; }
.options .bar i { position: absolute; inset: 0 auto 0 0; background: var(--dots); background-size: 3px 3px; transition: width .35s var(--ease-liquid); }
.options .why { font-size: 12px; color: var(--dim); text-align: right; }
.options li.masked .name { color: var(--faint); text-decoration: line-through; }
.options li.masked .bar i { opacity: .35; }
.options li.masked .bar::after { content: ""; position: absolute; left: 0; right: 0; top: 50%; height: 1.5px; background: var(--ink); }
.options li.chosen .why { color: var(--ink); font-weight: 600; }

/* Physics */
.bar-ctl { display: flex; flex-wrap: wrap; align-items: center; gap: 10px 14px; padding-bottom: 12px; margin-bottom: 12px; border-bottom: 1px solid var(--ink); }
.seg { display: inline-flex; border: 1px solid var(--ink); }
.seg button { border: 0; background: none; padding: 6px 10px; font: 500 12px/1 var(--mono); cursor: pointer; }
.seg button[aria-checked="true"] { background: var(--ink); color: var(--paper); }
.loss { margin-left: auto; font: 500 12px/1 var(--mono); color: var(--dim); font-variant-numeric: tabular-nums; }
.loss.training { color: var(--signal); }
#physics-canvas { display: block; width: 100%; height: auto; touch-action: none; cursor: default; }

/* ---- 03: start ------------------------------------------------------------------ */
.installs { display: flex; flex-wrap: wrap; gap: 12px; }
.install.big { font-size: clamp(16px, 2vw, 22px); padding: 16px 22px; }
.install.big:first-child { background: var(--learn); border-color: var(--learn); color: #fff; }
.install.big:first-child:hover { background: transparent; color: var(--learn); }
.install.big + .install.big { background: transparent; color: var(--ink); }
.install.big + .install.big:hover { background: var(--ink); color: var(--paper); }
.hello { display: grid; grid-template-columns: minmax(0, 8fr) minmax(0, 4fr); gap: 48px; margin-top: 48px; align-items: start; }
.hello-run .out {
  margin: 16px 0 0; padding: 14px 0 0; border-top: 1px solid var(--ink); min-height: 7em;
  font: 400 14px/1.6 var(--mono); white-space: pre-wrap; color: var(--ink-2);
}
.hello-run .out b { color: var(--ink); font-weight: 600; }
@media (max-width: 960px) { .hello { grid-template-columns: minmax(0, 1fr); gap: 24px; } }
.links { display: flex; flex-wrap: wrap; gap: 0; margin-top: 72px; border-top: 1px solid var(--rule); }
.links a { padding: 16px 20px 16px 0; margin-right: 20px; font: 500 14px/1 var(--mono); color: var(--ink); text-decoration: none; }
.links a:hover { text-decoration: underline; text-underline-offset: 4px; }
.alpha { margin: 8px 0 0; font: 400 13px/1.55 var(--mono); color: var(--faint); max-width: 70ch; }
.alpha a { color: var(--dim); }

@media (prefers-reduced-motion: reduce) {
  .phase, .hl-line, .sup span, .options .bar i { transition: none !important; }
}
.served.training { color: var(--signal); }

/* Training: the signal runs backward (upward) through what can learn, and through
   written code only where it is differentiable (.grad). Written lines stay still. */
.code.training .ln[data-phase="learned"]::after {
  background-image: radial-gradient(circle at center, var(--signal) 0 .9px, transparent 1.25px);
  background-size: 2px 4px;
  animation: backprop .42s linear infinite;
}
.code.training .ln.grad::after { background: var(--signal); }
@keyframes backprop { to { background-position: 0 -4px; } }
@media (prefers-reduced-motion: reduce) { .code.training .ln[data-phase="learned"]::after { animation: none; } }

@media (max-width: 640px) {
  .code .ln { padding-left: 36px; }
  .code .ln::before { width: 18px; }
  .code .ln::after { left: 26px; }
  #hero-code { --code-size: 12px; }
  .rules-code .ln.blocking::after { left: 23px; }
}

/* Spot colour on superposed values: while a value is uncertain its candidates print in
   the learned ink; the one that wins sets in black. */
.sup span { color: rgb(var(--learn-rgb)); }
.sup span[style*="filter: none"] { color: var(--ink); }


/* ---- 02: robots. A recorded run fills the section; the type sits on it. ---------- */
.reel { position: relative; display: flex; align-items: flex-end; min-height: 100svh; overflow: hidden; background: #0f0f0e; color: #f7f5ef; }
.reel-video { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; }
.reel::after { content: ""; position: absolute; inset: 0; background: rgb(15 15 14 / .42); pointer-events: none; }
.reel-body { position: relative; z-index: 1; padding-top: 160px; padding-bottom: 88px; }
.reel .label { color: #f7f5ef; }
.reel .h2 { max-width: 13ch; }
.reel-line { margin: 0 0 20px; max-width: 32ch; font-size: clamp(19px, 1.9vw, 26px); line-height: 1.35; }
.reel-fine { margin: 0; max-width: 64ch; font: 400 13px/1.55 var(--mono); color: rgb(247 245 239 / .78); }
.reel-fine a { color: #f7f5ef; }
@media (max-width: 760px) { .reel-body { padding-top: 120px; padding-bottom: 56px; } }