/* TellMom build booklet. One world: instruction-booklet pages on sky blue,
   white callouts, black line work, yellow for attention, red only on things
   you can press. */

:root {
  --sky: #c4e3f3;
  --sky-face: #a9d3ea;
  --sky-light: #e8f4fa;
  --paper: #ffffff;
  --ink: #14181f;
  --ink-2: #34485a;
  --ink-3: #5a6f82;
  --signal: #ffcf1a;
  --signal-deep: #8a6a00;
  --action: #cf2a16;
  --action-press: #a91f0f;
  --board: #3f8f5a;
  --chip: #2a3240;
  --code-bg: #14181f;
  --code-ink: #e8f4fa;
  --code-dim: #8fa6b8;

  --font: "Archivo", "Helvetica Neue", Arial, sans-serif;
  --mono: "JetBrains Mono", ui-monospace, "SFMono-Regular", Menlo, monospace;

  --gutter: clamp(16px, 4vw, 56px);
  --radius: 14px;
  --radius-sm: 8px;
  --line: 2px;
  --shadow: 0 10px 24px -12px rgb(20 24 31 / 0.35), 0 2px 4px rgb(20 24 31 / 0.08);

  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  color-scheme: light;
}

*,
*::before,
*::after { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: 76px;
  scrollbar-color: var(--ink-2) var(--sky);
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  background: var(--sky);
  color: var(--ink);
  font-family: var(--font);
  font-size: 1.0625rem;
  line-height: 1.55;
  font-variation-settings: "wdth" 100;
  caret-color: var(--action);
  -webkit-font-smoothing: antialiased;
}

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

a { color: inherit; text-underline-offset: 0.2em; text-decoration-thickness: 2px; }
a:hover { text-decoration-color: var(--action); }

:focus-visible {
  outline: 3px solid var(--ink);
  outline-offset: 3px;
  border-radius: 6px;
}

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

code, kbd, pre { font-family: var(--mono); font-size: 0.9em; }

.visually-hidden {
  position: absolute !important;
  width: 1px; height: 1px;
  overflow: hidden; clip: rect(0 0 0 0);
  white-space: nowrap;
}

/* Line-drawing faces, shared by every isometric drawing */
.iso polygon, .iso path, .iso ellipse, .iso line {
  stroke: var(--ink);
  stroke-width: 1.6;
  stroke-linejoin: round;
  vector-effect: non-scaling-stroke;
}
.iso .f-top { fill: var(--paper); }
.iso .f-r { fill: var(--sky-light); }
.iso .f-l { fill: var(--sky-face); }
.iso .f-green { fill: var(--board); }
.iso .f-dark { fill: var(--chip); }
.iso .f-signal { fill: var(--signal); }
.iso .f-action { fill: var(--action); }
.iso .f-sky { fill: var(--sky); }
.iso .ln, .iso .ln-thin { fill: none; }

/* ---------- Buttons: the only place the action colour lives ---------- */

.btn {
  --btn-bg: var(--action);
  display: inline-flex;
  align-items: center;
  gap: 0.6em;
  min-height: 48px;
  padding: 0.7em 1.35em;
  border: var(--line) solid var(--ink);
  border-radius: 999px;
  background: var(--btn-bg);
  color: #fff;
  font: inherit;
  font-weight: 750;
  font-variation-settings: "wdth" 110;
  letter-spacing: 0.005em;
  text-decoration: none;
  cursor: pointer;
  box-shadow: inset 0 -3px 0 rgb(0 0 0 / 0.25), 0 6px 14px -6px rgb(20 24 31 / 0.5);
  transition: transform 160ms var(--ease-out), box-shadow 160ms var(--ease-out), background 160ms;
}
.btn:hover { background: var(--action-press); text-decoration: none; }
.btn:active { transform: translateY(2px); box-shadow: inset 0 -1px 0 rgb(0 0 0 / 0.25), 0 2px 4px -2px rgb(20 24 31 / 0.5); }
.btn svg { width: 1.1em; height: 1.1em; }
.btn[disabled] { background: var(--ink-3); cursor: not-allowed; box-shadow: none; }

.btn-quiet {
  display: inline-flex;
  align-items: center;
  gap: 0.5em;
  min-height: 48px;
  padding: 0.7em 0.2em;
  border: 0;
  background: none;
  color: var(--ink);
  font: inherit;
  font-weight: 650;
  text-decoration: underline;
  text-decoration-thickness: 2px;
  text-underline-offset: 0.25em;
  cursor: pointer;
}
.btn-quiet:hover { text-decoration-color: var(--action); }

.btn-small {
  min-height: 36px;
  padding: 0.35em 0.9em;
  font-size: 0.9rem;
}

/* ---------- Page chrome ---------- */

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  gap: 24px;
  padding: 10px var(--gutter);
  background: rgb(196 227 243 / 0.92);
  backdrop-filter: saturate(1.4) blur(8px);
  border-bottom: var(--line) solid var(--ink);
}
.wordmark {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 900;
  font-size: 1.35rem;
  font-variation-settings: "wdth" 125;
  letter-spacing: -0.02em;
  text-decoration: none;
}
.wordmark svg { width: 38px; height: 38px; }
.topnav {
  display: flex;
  gap: 4px;
  margin-left: auto;
}
.topnav a {
  padding: 8px 12px;
  border-radius: 999px;
  font-weight: 600;
  text-decoration: none;
}
.topnav a:hover { background: var(--paper); }
.topnav a span {
  display: inline-block;
  min-width: 1.6em;
  margin-right: 4px;
  font-variant-numeric: tabular-nums;
  color: var(--ink-2);
  font-weight: 700;
}
.topbar .btn { min-height: 42px; padding: 0.45em 1.1em; }

.page {
  position: relative;
  padding: clamp(56px, 9vw, 120px) var(--gutter) clamp(72px, 9vw, 112px);
  border-bottom: var(--line) solid var(--ink);
}
.page-inner { max-width: 1320px; margin: 0 auto; }

h1, h2, h3 { margin: 0; text-wrap: balance; }
h2 {
  font-size: clamp(2.4rem, 5.4vw, 4.6rem);
  line-height: 0.98;
  font-weight: 850;
  font-variation-settings: "wdth" 115;
  letter-spacing: -0.03em;
  margin-bottom: 0.4em;
}
h3 {
  font-size: 1.3rem;
  line-height: 1.2;
  font-weight: 780;
  font-variation-settings: "wdth" 105;
  letter-spacing: -0.01em;
}
.lede {
  max-width: 62ch;
  font-size: clamp(1.1rem, 1.6vw, 1.3rem);
  line-height: 1.5;
  color: var(--ink-2);
  margin: 0;
}
.lede strong { color: var(--ink); }

.code-sm { width: 24px; height: 24px; font-size: 0.8rem; border-radius: 6px; vertical-align: 2px; margin-right: 4px; }

/* part code: the lettered chip that ties parts, diagram and steps together */
.code {
  display: inline-grid;
  place-items: center;
  flex: none;
  width: 30px;
  height: 30px;
  border-radius: 8px;
  background: var(--ink);
  color: var(--paper);
  font-weight: 850;
  font-size: 0.95rem;
  font-variation-settings: "wdth" 110;
  line-height: 1;
}

.callout {
  background: var(--paper);
  border: var(--line) solid var(--ink);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

/* ---------- 1 · Cover ---------- */

.cover {
  padding-top: clamp(36px, 5vw, 64px);
}
.cover-grid {
  display: grid;
  grid-template-columns: minmax(0, 5fr) minmax(0, 6fr);
  gap: clamp(32px, 5vw, 72px);
  align-items: center;
  margin-bottom: clamp(40px, 5vw, 64px);
}
.cover h1 {
  font-size: clamp(3.6rem, 8vw, 7.4rem);
  line-height: 0.84;
  font-weight: 900;
  font-variation-settings: "wdth" 125;
  letter-spacing: -0.045em;
  margin: 0 0 0.3em -0.04em;
}
.cover .promise {
  max-width: 32ch;
  margin: 0 0 1.6em;
  font-size: clamp(1.2rem, 1.9vw, 1.6rem);
  line-height: 1.35;
  font-weight: 560;
  letter-spacing: -0.01em;
}
.cover .promise mark {
  background: linear-gradient(transparent 58%, var(--signal) 58%);
  color: inherit;
  padding: 0 0.08em;
}
.cover-actions { display: flex; flex-wrap: wrap; align-items: center; gap: 12px 28px; }

/* photos mounted like box-art insets: white mat, ink outline, a slight tilt */
.collage {
  position: relative;
  aspect-ratio: 6 / 5;
}
.snap {
  position: absolute;
  margin: 0;
  padding: 8px;
  background: var(--paper);
  border: var(--line) solid var(--ink);
  border-radius: 22px;
  box-shadow: var(--shadow);
  overflow: hidden;
}
.snap img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 15px;
}
.snap-main { top: 0; right: 0; width: 84%; height: 74%; }
.snap-game { left: 0; bottom: 0; width: 50%; height: 40%; transform: rotate(-3deg); }
.snap-laugh { right: 6%; bottom: 2%; width: 34%; height: 30%; transform: rotate(4deg); }
.snap-main img { object-position: 50% 40%; }

/* the parts list: one strip under the cover */
.parts { padding: 18px 22px 16px; }
.parts header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  padding-bottom: 12px;
  margin-bottom: 8px;
  border-bottom: var(--line) solid var(--ink);
}
.parts header h2 {
  font-size: 1.2rem;
  margin: 0;
  letter-spacing: -0.01em;
  font-variation-settings: "wdth" 110;
}
.parts header span { color: var(--ink-2); font-size: 0.9rem; }
.parts ol {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 16px;
}
.parts li {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  grid-template-rows: auto auto;
  column-gap: 10px;
  align-items: center;
}
.parts li .code { grid-row: 1; }
.parts li svg { grid-row: 1; width: 60px; height: 60px; }
.parts li div { grid-column: 1 / -1; }
.parts li strong { display: block; font-weight: 750; line-height: 1.2; }
.parts li p { margin: 2px 0 0; font-size: 0.9rem; line-height: 1.35; color: var(--ink-2); }

/* ---------- 2 · Protocol ---------- */

.protocol-head {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: clamp(24px, 4vw, 64px);
  align-items: end;
  margin-bottom: clamp(40px, 6vw, 72px);
}
.protocol-head .lede { justify-self: end; }

.route {
  position: relative;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(16px, 3vw, 40px);
}
.station { position: relative; display: flex; flex-direction: column; }
.station-figure {
  position: relative;
  z-index: 1;
  display: grid;
  place-items: center;
  height: 170px;
}
.station-figure svg { width: 150px; height: 150px; }
.station-name {
  display: flex;
  align-items: center;
  gap: 10px;
  justify-content: center;
  margin: 6px 0 16px;
  font-weight: 750;
  font-size: 1.1rem;
}
.station-name small { font-weight: 500; color: var(--ink-2); font-size: 0.9rem; }

/* the pipe the packet travels along */
.pipe {
  position: absolute;
  top: 136px;
  left: calc(100% / 6);
  right: calc(100% / 6);
  height: 16px;
  border: var(--line) solid var(--ink);
  border-radius: 999px;
  background: repeating-linear-gradient(90deg, var(--sky-light) 0 22px, var(--paper) 22px 44px);
}
.packet {
  position: absolute;
  top: 50%;
  left: 0;
  width: 34px;
  height: 34px;
  margin: -17px 0 0 -17px;
  border: var(--line) solid var(--ink);
  border-radius: 7px;
  background: var(--paper);
  transform: rotate(45deg) scale(0.9);
  opacity: 0;
}
.packet.sealed { background: var(--chip); }
.packet.run { animation: travel 2.6s var(--ease-out) forwards; }
/* a live alert travels home-to-browser: right to left, sealed through the middle */
@keyframes travel {
  0% { left: 100%; opacity: 0; background: var(--paper); }
  8% { opacity: 1; }
  30% { background: var(--paper); }
  36% { background: var(--chip); }
  64% { background: var(--chip); }
  70% { background: var(--paper); }
  92% { opacity: 1; }
  100% { left: 0%; opacity: 0; background: var(--paper); }
}


/* what each part does to the box, under its drawing */
.station .station-name { height: 34px; margin: 0 0 4px; }
.station-says {
  margin: 4px 0 0;
  text-align: center;
  font-weight: 700;
  font-size: 1.05rem;
}
.station:nth-child(3) .station-says { color: var(--ink-2); }

/* the two columns: what it sees / what it never sees */
.sees {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: clamp(16px, 2.4vw, 32px);
  margin-top: clamp(40px, 5vw, 64px);
}
.sees-col { padding: 24px 26px 26px; }
.sees-col h3 {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: clamp(1.35rem, 2vw, 1.7rem);
  font-variation-settings: "wdth" 110;
  margin-bottom: 18px;
}
.sees-col h3 svg { width: 30px; height: 30px; flex: none; }
.example {
  margin-bottom: 18px;
  padding: 14px 16px;
  border-radius: 12px;
}
.example-label {
  margin: 0 0 8px;
  font-size: 0.85rem;
  font-weight: 650;
}
.example.locked { background: var(--code-bg); color: var(--code-dim); }
.example.locked .example-label { color: var(--code-ink); }
.cipher {
  margin: 0;
  font-family: var(--mono);
  font-size: 0.85rem;
  line-height: 1.55;
  word-break: break-all;
  min-height: 4.65em;
}
.cipher.fresh { animation: flash 900ms var(--ease-out); }
@keyframes flash { from { color: var(--signal); } to { color: var(--code-dim); } }
.example.open { background: var(--sky-light); }
.example.open .example-label { color: var(--ink-2); }
.alert-card {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 12px 14px;
  border: var(--line) solid var(--ink);
  border-radius: 12px;
  background: var(--paper);
}
.alert-risk {
  flex: none;
  display: grid;
  place-items: center;
  width: 64px;
  height: 64px;
  border: var(--line) solid var(--ink);
  border-radius: 10px;
  background: var(--signal);
  font-size: 1.4rem;
  font-weight: 900;
  font-variation-settings: "wdth" 80;
  font-variant-numeric: tabular-nums;
}
.alert-who { margin: 0; font-size: 0.9rem; font-weight: 700; }
.alert-msg { margin: 2px 0 0; font-size: 1.05rem; line-height: 1.35; }

.plain-list { list-style: none; margin: 0; padding: 0; }
.plain-list li {
  position: relative;
  padding: 10px 0 10px 30px;
  font-size: 1.1rem;
  line-height: 1.4;
}
.plain-list li + li { border-top: 1px dashed var(--sky-face); }
.plain-list li::before {
  content: "";
  position: absolute;
  left: 4px;
  top: 17px;
  width: 12px;
  height: 12px;
  border: var(--line) solid var(--ink);
  border-radius: 50%;
}
#sees-no ~ .plain-list li::before { background: var(--ink); }

.caveat {
  max-width: 70ch;
  margin: 28px 0 0;
  color: var(--ink-2);
}
.caveat strong { color: var(--ink); }

.route-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 24px;
  align-items: center;
  margin-top: 20px;
}
.route-actions p { margin: 0; color: var(--ink-2); font-size: 0.95rem; max-width: 62ch; }

/* sub-assembly frame */
.subassembly {
  position: relative;
  margin-top: 32px;
  border: var(--line) solid var(--ink);
  border-radius: 22px;
  background: var(--sky-light);
}
.subassembly summary {
  display: flex;
  align-items: center;
  gap: 8px 16px;
  flex-wrap: wrap;
  padding: 18px 24px;
  cursor: pointer;
  list-style: none;
  border-radius: 20px;
}
.subassembly summary::-webkit-details-marker { display: none; }
.subassembly summary span { font-size: 1.2rem; font-weight: 780; }
.subassembly summary small { color: var(--ink-2); font-size: 0.95rem; }
.subassembly summary .chev {
  width: 26px;
  height: 26px;
  margin-left: auto;
  padding: 2px;
  border: var(--line) solid var(--ink);
  border-radius: 50%;
  background: var(--paper);
  transition: transform 240ms var(--ease-out);
}
.subassembly summary:hover .chev { background: var(--signal); }
.subassembly[open] summary .chev { transform: rotate(180deg); }
.subassembly[open] summary { border-bottom: var(--line) solid var(--ink); border-radius: 20px 20px 0 0; }
.subassembly .handshake { padding: 28px 28px 8px; }
.fine {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 24px;
  margin: 12px 28px 28px;
  padding-top: 20px;
  border-top: 1px dashed var(--ink-3);
}
.fine h4 { margin: 0 0 6px; font-size: 1rem; }
.fine p { margin: 0; font-size: 0.95rem; color: var(--ink-2); line-height: 1.5; }
.handshake {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: clamp(20px, 3vw, 44px);
  counter-reset: hs;
}
.handshake li { position: relative; }
.handshake li:not(:last-child)::after {
  content: "";
  position: absolute;
  top: 26px;
  right: calc(-1 * clamp(20px, 3vw, 44px) + 4px);
  width: calc(clamp(20px, 3vw, 44px) - 8px);
  height: 2px;
  background: var(--ink);
}
.handshake li:not(:last-child)::before {
  content: "";
  position: absolute;
  top: 21px;
  right: calc(-1 * clamp(20px, 3vw, 44px) + 4px);
  width: 10px;
  height: 10px;
  border-top: 2px solid var(--ink);
  border-right: 2px solid var(--ink);
  transform: rotate(45deg);
}
.handshake .n {
  display: block;
  font-size: 3.3rem;
  line-height: 1;
  font-weight: 900;
  font-variation-settings: "wdth" 80;
  font-variant-numeric: tabular-nums;
  margin-bottom: 8px;
}
.handshake h4 { margin: 0 0 6px; font-size: 1.12rem; font-weight: 780; }
.handshake p { margin: 0; font-size: 0.95rem; line-height: 1.45; color: var(--ink-2); }
.handshake code { background: var(--paper); padding: 0.05em 0.3em; border-radius: 4px; color: var(--ink); }

/* ledger */
/* ---------- 4–8 · Build flow ---------- */

.build-head {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: end;
  gap: 16px 48px;
  margin-bottom: clamp(36px, 5vw, 56px);
}

.flow {
  list-style: none;
  margin: 0 0 28px;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 14px;
}
.flow li { position: relative; }
.flow li:not(:last-child)::after {
  content: "";
  position: absolute;
  z-index: 2;
  top: 40px;
  right: -16px;
  width: 18px;
  height: 18px;
  border-top: 3px solid var(--ink);
  border-right: 3px solid var(--ink);
  transform: rotate(45deg);
  background: transparent;
}
.step-btn {
  position: relative;
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  grid-template-rows: auto auto;
  column-gap: 12px;
  align-items: center;
  width: 100%;
  height: 100%;
  padding: 14px 16px 18px;
  border: var(--line) solid transparent;
  border-radius: var(--radius);
  background: transparent;
  color: inherit;
  font: inherit;
  text-align: left;
  cursor: pointer;
  transition: background 240ms var(--ease-out), border-color 240ms, box-shadow 240ms;
}
.step-btn:hover { background: rgb(255 255 255 / 0.55); }
.step-btn[aria-selected="true"] {
  background: var(--paper);
  border-color: var(--ink);
  box-shadow: var(--shadow);
}
.step-btn .n {
  grid-row: span 2;
  font-size: 4rem;
  line-height: 0.9;
  font-weight: 900;
  font-variation-settings: "wdth" 75;
  font-variant-numeric: tabular-nums;
}
.step-btn .t { font-weight: 760; line-height: 1.2; font-size: 1.02rem; }
.step-btn .p {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  color: var(--ink-2);
  margin-top: 6px;
}
.step-btn .p .code { width: 22px; height: 22px; font-size: 0.75rem; border-radius: 6px; }
.step-btn .bar {
  position: absolute;
  left: 16px;
  right: 16px;
  bottom: 8px;
  height: 3px;
  border-radius: 2px;
  background: var(--sky-light);
  overflow: hidden;
  opacity: 0;
}
.step-btn[aria-selected="true"] .bar { opacity: 1; }
.step-btn .bar i {
  display: block;
  height: 100%;
  width: 100%;
  background: var(--ink);
  transform-origin: left;
  transform: scaleX(0);
}

.stage { position: relative; }
.panel {
  display: grid;
  grid-template-columns: minmax(0, 1.45fr) minmax(0, 1fr);
  gap: clamp(20px, 3vw, 40px);
  align-items: start;
}
.panel[hidden] { display: none; }
.media {
  position: relative;
  aspect-ratio: 16 / 10;
  overflow: hidden;
  border: 3px solid var(--ink);
  border-radius: 20px;
  background: var(--paper);
  box-shadow: var(--shadow);
}
.media video {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  background: var(--ink);
}
.media .placeholder {
  position: absolute;
  inset: 0;
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 24px;
  text-align: center;
  background:
    linear-gradient(var(--sky-face) 1px, transparent 1px) 0 0 / 28px 28px,
    linear-gradient(90deg, var(--sky-face) 1px, transparent 1px) 0 0 / 28px 28px,
    var(--sky-light);
}
.media .placeholder svg { width: min(46%, 240px); height: auto; }
.media .placeholder p { margin: 0; color: var(--ink-2); font-size: 0.95rem; }
.media.missing video { display: none; }
.media.missing .placeholder { display: flex; }

.detail h3 {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: clamp(1.5rem, 2.4vw, 2rem);
  font-variation-settings: "wdth" 110;
  margin-bottom: 12px;
}
.detail > p { margin: 0 0 18px; color: var(--ink-2); max-width: 52ch; }
.detail > p strong { color: var(--ink); }

.cmd {
  position: relative;
  margin: 0 0 14px;
  border-radius: var(--radius-sm);
  background: var(--code-bg);
  color: var(--code-ink);
  border: var(--line) solid var(--ink);
}
.cmd pre {
  margin: 0;
  padding: 14px 16px;
  padding-right: 88px;
  overflow-x: auto;
  font-size: 0.86rem;
  line-height: 1.7;
  scrollbar-color: var(--ink-3) var(--code-bg);
}
.cmd pre .c { color: var(--code-dim); }
.cmd pre .v { color: var(--signal); }
.copy {
  position: absolute;
  top: 8px;
  right: 8px;
  min-height: 32px;
  padding: 4px 12px;
  border: 1px solid var(--code-dim);
  border-radius: 999px;
  background: transparent;
  color: var(--code-ink);
  font: inherit;
  font-size: 0.8rem;
  font-weight: 650;
  cursor: pointer;
}
.copy:hover { border-color: var(--code-ink); }
.copy.done { background: var(--signal); color: var(--ink); border-color: var(--signal); }

.detail .aside {
  margin: 4px 0 0;
  padding-left: 14px;
  border-left: 1px solid var(--ink);
  font-size: 0.93rem;
  color: var(--ink-2);
  max-width: 52ch;
}

/* ---------- 9 · Playground ---------- */

.play-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr);
  gap: clamp(20px, 3vw, 44px);
  align-items: start;
  margin-top: clamp(32px, 4vw, 48px);
}
.chat { display: flex; flex-direction: column; overflow: hidden; }
.chat-head {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 12px;
  align-items: center;
  justify-content: space-between;
  padding: 14px 18px;
  border-bottom: var(--line) solid var(--ink);
}
.chat-head .transport { display: flex; align-items: center; gap: 14px; }
.chat-head .btn-quiet { min-height: 36px; padding: 0; }
.presets { display: flex; gap: 6px; flex-wrap: wrap; }
.preset {
  min-height: 36px;
  padding: 4px 12px;
  border: var(--line) solid var(--ink);
  border-radius: 999px;
  background: var(--paper);
  color: var(--ink);
  font: inherit;
  font-size: 0.88rem;
  font-weight: 650;
  cursor: pointer;
}
.preset[aria-pressed="true"] { background: var(--ink); color: var(--paper); }

.log {
  list-style: none;
  margin: 0;
  padding: 16px 18px;
  height: 420px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 8px;
  background:
    linear-gradient(var(--sky-light) 1px, transparent 1px) 0 0 / 100% 28px,
    var(--paper);
  scrollbar-color: var(--sky-face) var(--paper);
}
.log:empty::before {
  content: "Pick a chat above and press Play, or type your own below.";
  margin: auto;
  color: var(--ink-3);
  text-align: center;
  max-width: 28ch;
}
.msg {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 2px 10px;
  max-width: 86%;
  animation: pop 420ms var(--ease-out);
}
.msg .who { font-size: 0.75rem; font-weight: 700; color: var(--ink-2); grid-column: 2; }
.msg .bubble {
  grid-column: 2;
  padding: 9px 14px;
  font-size: 1.05rem;
  border: var(--line) solid var(--ink);
  border-radius: 16px 16px 16px 4px;
  background: var(--sky-light);
  line-height: 1.35;
  overflow-wrap: anywhere;
}
.msg .idx {
  grid-row: span 2;
  align-self: end;
  font-size: 0.75rem;
  font-weight: 800;
  color: var(--ink-3);
  font-variant-numeric: tabular-nums;
  min-width: 1.4em;
  text-align: right;
}
.msg.child { align-self: flex-end; grid-template-columns: minmax(0, 1fr) auto; }
.msg.child .who, .msg.child .bubble { grid-column: 1; text-align: right; }
.msg.child .bubble { background: var(--signal); border-radius: 14px 14px 4px 14px; text-align: left; }
.msg.child .idx { grid-column: 2; grid-row: 1 / span 2; text-align: left; }
@keyframes pop { from { opacity: 0; transform: translateY(8px) scale(0.98); } to { opacity: 1; transform: none; } }

.compose {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  gap: 8px;
  padding: 12px;
  border-top: var(--line) solid var(--ink);
  background: var(--sky-light);
}
.compose select, .compose input {
  min-height: 44px;
  padding: 8px 12px;
  border: var(--line) solid var(--ink);
  border-radius: 10px;
  background: var(--paper);
  color: var(--ink);
  font: inherit;
  font-size: 0.95rem;
}
.compose input::placeholder { color: var(--ink-3); }
.compose .btn { min-height: 44px; padding: 0.4em 1.1em; }

/* the result: one plain sentence first, then the number */
.result { padding: 24px 26px 22px; }
.verdict {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  margin-bottom: 22px;
  padding: 16px 18px;
  border: var(--line) solid var(--ink);
  border-radius: 14px;
  background: var(--sky-light);
  transition: background 300ms var(--ease-out);
}
.verdict-icon {
  flex: none;
  display: grid;
  place-items: center;
  width: 44px;
  height: 44px;
  border: var(--line) solid var(--ink);
  border-radius: 50%;
  background: var(--paper);
}
.verdict-icon svg { width: 24px; height: 24px; }
.verdict-title {
  margin: 0;
  font-size: clamp(1.3rem, 2vw, 1.6rem);
  font-weight: 820;
  font-variation-settings: "wdth" 108;
  line-height: 1.15;
}
.verdict-sub { margin: 4px 0 0; color: var(--ink-2); font-size: 0.98rem; line-height: 1.4; }
.verdict.ok { background: #e6f3ea; }
.verdict.ok .verdict-icon { background: var(--board); color: #fff; }
.verdict.flagged { background: var(--signal); }
.verdict.flagged .verdict-icon { background: var(--ink); color: var(--signal); }
.verdict.error { background: var(--paper); border-style: dashed; }

.gauge-head {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  margin-bottom: 12px;
}
.gauge-head > span { font-weight: 750; font-size: 1.1rem; padding-bottom: 6px; }
.digits { display: flex; align-items: flex-end; gap: 5px; }
.digit {
  position: relative;
  width: 58px;
  height: 80px;
  overflow: hidden;
  border: var(--line) solid var(--ink);
  border-radius: 10px;
  background: var(--sky-light);
}
.digit .reel {
  position: absolute;
  inset: 0 0 auto 0;
  transition: transform 700ms var(--ease-out);
}
.digit .reel span {
  display: grid;
  place-items: center;
  height: 76px;
  font-size: 3.6rem;
  font-weight: 850;
  font-variation-settings: "wdth" 80;
  font-variant-numeric: tabular-nums;
  line-height: 1;
}
.pct { font-size: 2rem; font-weight: 850; padding: 0 0 8px 4px; }
.digits.idle .reel { opacity: 0.2; }
.digits.flagged .digit { background: var(--signal); }

.meter {
  position: relative;
  height: 22px;
  border: var(--line) solid var(--ink);
  border-radius: 999px;
  background: var(--paper);
  overflow: visible;
}
.meter-fill {
  position: absolute;
  inset: 0 auto 0 0;
  width: 100%;
  border-radius: 999px;
  background: var(--board);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 700ms var(--ease-out), background 300ms;
}
.meter-fill.hot { background: var(--signal); box-shadow: inset 0 0 0 2px var(--ink); }
.meter-line {
  position: absolute;
  top: -8px;
  bottom: -8px;
  left: 50%;
  width: 3px;
  margin-left: -1.5px;
  background: var(--ink);
  border-radius: 2px;
}
.meter-line span {
  position: absolute;
  bottom: calc(100% + 4px);
  left: 50%;
  transform: translateX(-50%);
  white-space: nowrap;
  font-size: 0.8rem;
  font-weight: 750;
}
.meter-scale {
  display: flex;
  justify-content: space-between;
  margin-top: 6px;
  font-size: 0.85rem;
  color: var(--ink-2);
}

/* seven dots: TellMom waits for seven messages before it judges */
.progress {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin: 22px 0 0;
  padding: 0;
}
.progress li {
  width: 16px;
  height: 16px;
  border: var(--line) solid var(--ink);
  border-radius: 50%;
  background: var(--paper);
  transition: background 200ms;
}
.progress li.read { background: var(--ink-2); }
.progress li.scored { background: var(--board); }
.progress li.hot { background: var(--signal); }
.result .fine { display: block; margin: 16px 0 0; padding: 0; border: 0; font-size: 0.9rem; color: var(--ink-2); line-height: 1.45; }

.stages {
  margin-top: clamp(48px, 6vw, 72px);
}
.stages > p { margin: 0 0 22px; max-width: 70ch; color: var(--ink-2); }
.sequence {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(7, minmax(0, 1fr));
  gap: 22px;
  counter-reset: st;
}
.sequence li {
  counter-increment: st;
  position: relative;
  padding-top: 10px;
  border-top: 3px solid var(--ink);
  font-weight: 700;
  font-size: 0.95rem;
  line-height: 1.25;
}
.sequence li::before {
  content: counter(st);
  display: block;
  margin-bottom: 6px;
  font-size: 2.8rem;
  font-weight: 900;
  font-variation-settings: "wdth" 75;
  line-height: 1;
}
/* leader to the next stage: the rule carries on across the gap into an arrowhead */
.sequence li:not(:last-child)::after {
  content: "";
  position: absolute;
  top: -8.5px;
  right: -17px;
  width: 11px;
  height: 11px;
  border-top: 3px solid var(--ink);
  border-right: 3px solid var(--ink);
  transform: rotate(45deg);
}
.sequence li:not(:last-child) { border-image: linear-gradient(var(--ink), var(--ink)) 1 / 3px 0 0 0 / 0 14px 0 0 stretch; }
.sequence li:not(:last-child)::marker { content: none; }

/* ---------- Back cover ---------- */

.back {
  background: var(--ink);
  color: var(--sky-light);
  border-bottom: 0;
}
.back h2 { color: var(--paper); font-size: clamp(3rem, 8vw, 6rem); font-variation-settings: "wdth" 125; }
.back .lede { color: var(--code-dim); }
.back .lede strong { color: var(--paper); }
.back-actions { display: flex; flex-wrap: wrap; gap: 12px 28px; align-items: center; margin: 32px 0 56px; }
.back .btn { border-color: #000; }
.back .btn-quiet { color: var(--paper); }
.back-notes {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 24px;
  padding-top: 24px;
  border-top: 1px solid #34485a;
  font-size: 0.92rem;
  color: var(--code-dim);
}
.back-notes h3 { font-size: 0.95rem; color: var(--paper); margin-bottom: 6px; }
.back-notes p { margin: 0; line-height: 1.5; }

/* ---------- Responsive ---------- */

@media (max-width: 1080px) {
  .topnav a span { display: none; }
  .flow .step-btn .n { font-size: 3.2rem; }
  .sequence { grid-template-columns: repeat(4, minmax(0, 1fr)); row-gap: 32px; }
  .sequence li:nth-child(4)::after { display: none; }
}

@media (max-width: 900px) {
  .topnav { display: none; }
  .topbar .btn { margin-left: auto; }
  .cover-grid,
  .protocol-head,
  .play-grid { grid-template-columns: minmax(0, 1fr); }
  .protocol-head .lede { justify-self: start; }
  .route { grid-template-columns: minmax(0, 1fr); gap: 28px; }
  .pipe { display: none; }
  .station-figure { height: 130px; }
  .station-figure svg { width: 120px; height: 120px; }
  .route { grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 8px; }
  .station .station-name { height: auto; min-height: 44px; font-size: 0.9rem; flex-direction: column; gap: 4px; margin: 0; text-align: center; }
  .station-figure { height: 96px; }
  .station-figure svg { width: 88px; height: 88px; }
  .station-says { font-size: 0.9rem; }
  .station:not(:last-child)::after {
    display: none;
    content: "";
    position: absolute;
    left: 50%;
    bottom: -24px;
    width: 12px;
    height: 12px;
    margin-left: -6px;
    border-bottom: 3px solid var(--ink);
    border-right: 3px solid var(--ink);
    transform: rotate(45deg);
  }
  .handshake { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .handshake li::after, .handshake li::before { display: none; }
  .sees, .fine { grid-template-columns: minmax(0, 1fr); }
  .parts ol { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .collage { max-width: 560px; }
  /* phones get every step stacked, each clip playing as it scrolls in */
  .flow { display: none; }
  .panel, .panel[hidden] { display: grid; grid-template-columns: minmax(0, 1fr); }
  .panel + .panel { margin-top: 56px; }
  .detail h3 .n-inline { display: inline; }
  .back-notes { grid-template-columns: 1fr; }
}

@media (max-width: 560px) {
  body { font-size: 1rem; }
  .parts { padding: 16px 16px 6px; }
  .parts ol { grid-template-columns: minmax(0, 1fr); gap: 12px; }
  .parts li { grid-template-columns: auto 48px minmax(0, 1fr); }
  .parts li svg { width: 48px; height: 48px; }
  .parts li div { grid-column: 3; grid-row: 1; }
  .subassembly .handshake { padding: 20px 18px 4px; }
  .fine { margin: 8px 18px 20px; }
  .handshake { grid-template-columns: 1fr; }
  .sequence { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .sequence li:nth-child(even)::after { display: none; }
  .sequence li:nth-child(4)::after { display: none; }
  .cmd pre { padding-top: 48px; padding-right: 16px; }
  .compose { grid-template-columns: 1fr auto; }
  .compose select { grid-column: 1 / -1; }
  .log { height: 360px; }
}

.n-inline { display: none; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: 1ms !important; transition-duration: 1ms !important; }
}