/* Page: anatomy light "paper" tokens, layout, step text, navigation. */
:root {
  --page: #f2f2ef;
  --card: #fbfbfa;
  --text: #57575a;
  --strong: #18181a;
  --muted: #8c8c90;
  --line: #d4d4d6;
  --line-strong: #b4b4b8;
  --hi: #26262a;
  --dmp: #007fc8;
  --dmp-soft: rgba(0, 127, 200, 0.14);
  --led: #e5484d;
  --mono: ui-monospace, "SF Mono", SFMono-Regular, Menlo, Consolas, monospace;
  --sans: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Segoe UI", system-ui, sans-serif;
  --ease-out: cubic-bezier(0.23, 1, 0.32, 1);
  --ease-in-out: cubic-bezier(0.77, 0, 0.175, 1);
  --ease-drawer: cubic-bezier(0.32, 0.72, 0, 1);
  --lift: inset 0 1px 0 0 #ffffff, 0 0 0 1px #0000000f, 0 1px 1px -0.5px #0000000a, 0 3px 3px -1.5px #0000000a,
    0 6px 6px -3px #0000000a, 0 12px 12px -6px #0000000a;
  --stage-h: min(clamp(440px, calc(100svh - 200px), 780px), calc((100vw - 470px) / 1.26));
  color-scheme: light;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--page);
  color: var(--text);
  font: 16px/1.55 var(--sans);
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
img { display: block; max-width: 100%; }
button { font: inherit; color: inherit; }

/* Header -------------------------------------------------------------- */
.top {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 12px clamp(16px, 3vw, 32px);
  background: color-mix(in srgb, var(--page) 88%, transparent);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 12px; min-width: 0; }
.brand img { height: 22px; width: auto; filter: brightness(0) saturate(100%); opacity: 0.86; }
.brand span {
  font: 500 11px/1 var(--mono);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.top .tools { margin-left: auto; display: flex; align-items: center; gap: 10px; }
.top .lang {
  font: 500 12.5px/1 var(--sans);
  color: var(--text);
  text-decoration: none;
  padding: 6px 11px;
  border-radius: 999px;
  transition: background-color 150ms ease, color 150ms ease;
}
.top .lang { font: 500 11px/1 var(--mono); letter-spacing: 0.08em; color: var(--strong); background: var(--card); box-shadow: var(--lift); padding: 8px 11px; }
.top .count {
  font: 500 11px/1 var(--mono);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

/* Progress: a ruler strip, one segment per step. ------------------------ */
.ruler {
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  gap: 3px;
  padding: 0 clamp(16px, 3vw, 32px);
  margin-top: 10px;
}
.ruler button {
  position: relative;
  appearance: none;
  border: 0;
  padding: 10px 0 6px;
  background: none;
  cursor: pointer;
  text-align: left;
  -webkit-tap-highlight-color: transparent;
}
.ruler button::before {
  content: "";
  display: block;
  height: 3px;
  border-radius: 2px;
  background: var(--line);
  transition: background-color 200ms ease;
}
.ruler .prog {
  position: absolute;
  left: 0;
  right: 0;
  top: 10px;
  height: 3px;
  border-radius: 2px;
  background: var(--hi);
  transform-origin: 0 50%;
  transform: scaleX(0);
}
.ruler button[data-done] .prog { transform: scaleX(1); }
.ruler button span {
  display: block;
  margin-top: 6px;
  font: 500 10px/1.2 var(--mono);
  letter-spacing: 0.06em;
  color: var(--muted);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.ruler button[aria-current="step"] span { color: var(--strong); }
@media (hover: hover) and (pointer: fine) {
  .ruler button:hover::before { background: var(--line-strong); }
  .ruler button[aria-current="step"]:hover::before { background: var(--line); }
}

/* Stage ---------------------------------------------------------------- */
main {
  padding: 18px clamp(16px, 3vw, 32px) 96px;
}
.step {
  display: grid;
  grid-template-columns: minmax(260px, 340px) 1fr;
  gap: clamp(20px, 3vw, 44px);
  align-items: start;
}
.step[hidden] { display: none; }
/* Steps change from the keyboard too: no movement, only a short fade so content doesn't teleport. */
.step.is-entering { animation: step-in 150ms var(--ease-out) both; }
@keyframes step-in { from { opacity: 0; } }

.copy { padding-top: 8px; }
.eyebrow {
  font: 500 11px/1 var(--mono);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 0 14px;
}
.copy h1 {
  margin: 0 0 14px;
  color: var(--strong);
  font-size: clamp(26px, 2.6vw, 34px);
  line-height: 1.12;
  letter-spacing: -0.02em;
  font-weight: 650;
  text-wrap: balance;
}
.copy p { margin: 0 0 12px; text-wrap: pretty; }
.copy strong { color: var(--strong); font-weight: 600; }
.copy p a { color: var(--dmp); font-weight: 600; text-decoration: underline; text-decoration-thickness: 1px; text-underline-offset: 3px; }
.copy ol { margin: 4px 0 12px; padding-left: 0; list-style: none; counter-reset: s; }
.copy ol li { counter-increment: s; display: flex; gap: 10px; padding: 6px 0; border-top: 1px solid var(--line); }
.copy ol li::before {
  content: counter(s);
  font: 500 11px/22px var(--mono);
  color: var(--muted);
  min-width: 14px;
}
.copy ol a { color: var(--strong); text-decoration: none; }
@media (hover: hover) and (pointer: fine) {
  .copy ol a:hover { text-decoration: underline; text-underline-offset: 3px; }
}
.litres {
  display: flex;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 2px 10px;
  margin: 0 0 16px;
  padding: 14px 18px 12px;
  border-radius: 12px;
  background: var(--card);
  box-shadow: var(--lift);
}
.litres .l-num { font: 700 clamp(46px, 5vw, 62px)/1 var(--sans); color: var(--dmp); letter-spacing: -0.03em; font-variant-numeric: tabular-nums; }
.litres .l-unit { font: 600 21px/1 var(--sans); color: var(--dmp); }
.litres .l-cap { flex-basis: 100%; margin-top: 8px; font: 500 10.5px/1.3 var(--mono); letter-spacing: 0.07em; text-transform: uppercase; color: var(--muted); }
.note {
  margin: 16px 0 0;
  padding: 12px 14px;
  border-radius: 10px;
  background: var(--card);
  box-shadow: var(--lift);
  font-size: 14px;
  line-height: 1.5;
}
.note b { display: block; font: 500 10.5px/1 var(--mono); letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); margin-bottom: 8px; }
.replay {
  margin-top: 18px;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  border: 0;
  border-radius: 999px;
  background: var(--card);
  box-shadow: var(--lift);
  font: 500 11px/1 var(--mono);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--strong);
  cursor: pointer;
  transition: transform 120ms var(--ease-out);
}
.replay:active { transform: scale(0.97); }
.replay svg { width: 12px; height: 12px; }

.visual {
  display: flex;
  gap: clamp(16px, 2.4vw, 32px);
  align-items: flex-start;
  justify-content: center;
  min-width: 0;
}
.visual > * { flex: 0 0 auto; min-width: 0; }

/* Footer navigation ---------------------------------------------------- */
.nav {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 20;
  display: flex;
  justify-content: space-between;
  gap: 12px;
  padding: 12px clamp(16px, 3vw, 32px) max(12px, env(safe-area-inset-bottom));
  background: color-mix(in srgb, var(--page) 88%, transparent);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-top: 1px solid var(--line);
}
.nav button {
  appearance: none;
  border: 0;
  border-radius: 999px;
  padding: 11px 20px;
  font: 600 15px/1 var(--sans);
  cursor: pointer;
  transition: transform 120ms var(--ease-out), opacity 150ms ease;
  -webkit-tap-highlight-color: transparent;
  touch-action: manipulation;
}
.nav button:active { transform: scale(0.97); }
.nav button:disabled { opacity: 0.35; cursor: default; transform: none; }
.nav .prev { background: var(--card); color: var(--strong); box-shadow: var(--lift); }
.nav .next { background: var(--hi); color: #fff; }
.nav .keys { align-self: center; font: 500 10.5px/1 var(--mono); letter-spacing: 0.06em; color: var(--muted); }

/* Responsive ------------------------------------------------------------ */
@media (max-width: 1180px) {
  .step { grid-template-columns: 1fr; }
  .copy { max-width: 640px; }
  :root { --stage-h: min(clamp(420px, calc(100svh - 210px), 720px), calc((100vw - 80px) / 1.26)); }
}
@media (max-width: 760px) {
  :root { --stage-h: clamp(420px, calc(100svh - 210px), 640px); }
  .visual { flex-direction: column; align-items: center; }
  .ruler button span { display: none; }
  .nav .keys { display: none; }
  .brand span { display: none; }
  .top .count { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  .step.is-entering { animation-duration: 120ms; }
}