:root {
  --paper: #E8ECF1;
  --paper-2: #F5F7FA;
  --card: #FFFFFF;
  --ink: #15193A;
  --ink-2: #4A5172;
  --line: #C9D0DB;
  --grid: rgba(21, 25, 58, 0.055);
  --yellow: #FFD21F;
  --green: #00A651;
  --red: #D3203A;
  --blue: #1258D6;
  --orange: #FF6A13;
  --focus: #1258D6;
  --display: 'Bricolage Grotesque', 'Segoe UI', system-ui, sans-serif;
  --body: 'Atkinson Hyperlegible', 'Segoe UI', system-ui, sans-serif;
  --gutter: clamp(16px, 4vw, 48px);
  --r-stage: 26px;
  --r-ctl: 12px;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  color: var(--ink);
  background-color: var(--paper);
  background-image:
    linear-gradient(var(--grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 28px 28px;
  font: 400 1.0625rem/1.6 var(--body);
  overflow-x: hidden;
}
img, svg, canvas { display: block; }
a { color: inherit; }
button { font: inherit; color: inherit; cursor: pointer; }
:focus-visible { outline: 3px solid var(--focus); outline-offset: 3px; border-radius: 6px; }
main { outline: none; padding: 0 var(--gutter) 96px; max-width: 1440px; margin: 0 auto; }
h1, h2, h3 { font-family: var(--display); line-height: 1.08; letter-spacing: -0.02em; margin: 0; }
h2 { font-size: clamp(1.5rem, 2.4vw, 2rem); font-weight: 700; }
p { margin: 0; }
.skip { position: absolute; left: -999px; top: 8px; background: var(--ink); color: #fff; padding: 8px 14px; border-radius: 8px; z-index: 10; }
.skip:focus { left: 12px; }
.noscript { padding: 40px var(--gutter); }

/* ---------- top bar ---------- */
.topbar {
  position: sticky; top: 0; z-index: 5;
  display: flex; align-items: center; justify-content: space-between; gap: 16px;
  padding: 12px var(--gutter);
  background: rgba(232, 236, 241, 0.86);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; font: 700 1.05rem var(--display); letter-spacing: -0.01em; }
.brand-mark { display: grid; grid-template-columns: repeat(2, 9px); gap: 2px; padding: 3px; background: var(--ink); border-radius: 6px; }
.brand-mark i { width: 9px; height: 9px; border-radius: 2px; }
.brand-mark i:nth-child(1) { background: var(--yellow); }
.brand-mark i:nth-child(2) { background: var(--green); }
.brand-mark i:nth-child(3) { background: var(--red); }
.brand-mark i:nth-child(4) { background: var(--blue); }
.nav { display: flex; gap: 4px; }
.nav a {
  text-decoration: none; padding: 7px 12px; border-radius: 999px; font-weight: 700; font-size: 0.95rem;
}
.nav a:hover { background: rgba(21, 25, 58, 0.07); }
.nav a[aria-current] { background: var(--ink); color: #fff; }

/* ---------- buttons ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 12px 20px; border-radius: var(--r-ctl);
  border: 2px solid var(--ink); background: var(--card);
  font-weight: 700; text-decoration: none; line-height: 1.2;
  transition: transform 0.12s ease, background 0.12s ease;
}
.btn:hover { transform: translateY(-1px); }
.btn:active { transform: translateY(1px); }
.btn-primary { background: var(--yellow); box-shadow: 0 3px 0 var(--ink); }
.btn-small { padding: 7px 12px; font-size: 0.9rem; border-width: 1.5px; }

/* ---------- stage (3D canvas host) ---------- */
.stage {
  position: relative;
  border-radius: var(--r-stage);
  background:
    radial-gradient(120% 90% at 50% 18%, #FFFFFF 0%, #EEF1F6 55%, #DCE2EA 100%);
  border: 1.5px solid var(--line);
  overflow: hidden;
  touch-action: pan-y;
}
.stage canvas { width: 100% !important; height: 100% !important; cursor: grab; }
.stage canvas:active { cursor: grabbing; }
.stage-cap {
  position: absolute; left: 18px; top: 16px; right: 120px; z-index: 1;
  font: 700 1rem/1.3 var(--display); pointer-events: none;
}
.stage-reset { position: absolute; right: 14px; top: 12px; z-index: 1; background: rgba(255,255,255,0.85); }
.tok {
  display: inline-block; min-width: 2.2ch; padding: 1px 8px; margin-right: 6px;
  border-radius: 8px; background: var(--ink); color: #fff; font: 800 1rem/1.5 var(--display); text-align: center;
}
.hold-legend {
  position: absolute; left: 16px; bottom: 14px; z-index: 1;
  display: flex; align-items: center; gap: 6px;
  padding: 6px 10px; border-radius: 999px; background: rgba(255,255,255,0.85);
  font-size: 0.85rem; font-weight: 700; pointer-events: none;
}
.hold-legend span + .sw { margin-left: 6px; }
.sw {
  display: inline-block; width: 14px; height: 14px; border-radius: 4px;
  background: var(--c); box-shadow: inset 0 0 0 1.5px rgba(21, 25, 58, 0.35); flex: none;
}

/* ---------- home ---------- */
.hero {
  display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1.05fr);
  gap: clamp(24px, 4vw, 64px); align-items: center;
  min-height: calc(100vh - 66px); padding: 32px 0;
}
.display {
  font-size: clamp(2.6rem, 6.2vw, 5.4rem); font-weight: 800; letter-spacing: -0.035em; line-height: 0.98;
  max-width: 13ch;
}
.lede { font-size: clamp(1.08rem, 1.4vw, 1.22rem); color: var(--ink-2); max-width: 54ch; margin-top: 20px; }
.cta { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 32px; }
.hint { margin-top: 20px; color: var(--ink-2); font-size: 0.98rem; max-width: 50ch; }
.hero-stage { height: min(72vh, 640px); background: radial-gradient(90% 80% at 50% 40%, #FFFFFF, #E4E9F0 70%); }
.route { padding: 40px 0 0; }
.route-list {
  list-style: none; padding: 0; margin: 24px 0 0;
  display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 0;
  border-top: 2px solid var(--ink); counter-reset: r;
}
.route-list li { counter-increment: r; border-right: 1px solid var(--line); }
.route-list li:last-child { border-right: 0; }
.route-list a {
  display: grid; gap: 8px; padding: 20px 20px 24px 0; margin-left: 20px; text-decoration: none; height: 100%;
}
.route-list li:first-child a { margin-left: 0; }
.route-list a::before { content: counter(r); font: 800 2.4rem/1 var(--display); color: var(--ink); }
.route-list strong { font: 700 1.2rem var(--display); display: flex; align-items: center; gap: 8px; }
.route-list span { color: var(--ink-2); font-size: 0.98rem; }
.route-list a:hover strong { text-decoration: underline; text-underline-offset: 4px; }

/* ---------- generic page head ---------- */
.page-head { padding: 40px 0 28px; max-width: 70ch; }
.page-head h1 { font-size: clamp(2.1rem, 4.4vw, 3.4rem); font-weight: 800; letter-spacing: -0.03em; }
.page-head .lede { margin-top: 12px; }

/* ---------- notation ---------- */
.split { display: grid; grid-template-columns: minmax(0, 1.2fr) minmax(320px, 0.9fr); gap: 28px; align-items: start; }
.split > .stage-col { position: relative; top: 0; }
.stage-tall { height: min(62vh, 560px); }
.panel { display: grid; gap: 18px; }
.panel h2 { font-size: 1.3rem; margin-top: 10px; }
.seg, .speed { display: inline-flex; padding: 3px; border-radius: 999px; background: rgba(21, 25, 58, 0.08); width: fit-content; }
.seg button, .speed button { border: 0; background: transparent; padding: 6px 14px; border-radius: 999px; font-weight: 700; font-size: 0.92rem; }
.seg button[aria-pressed="true"], .speed button[aria-pressed="true"] { background: var(--ink); color: #fff; }
.faces { list-style: none; padding: 0; margin: 0; display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 8px 18px; }
.faces li { display: grid; grid-template-columns: auto 2ch 1fr auto; align-items: center; gap: 10px; padding: 6px 0; border-bottom: 1px solid var(--line); }
.faces b { font: 800 1.2rem var(--display); }
.faces em { color: var(--ink-2); font-size: 0.85rem; font-style: normal; }
.mods { margin: 0; display: grid; gap: 8px; }
.mods div { display: grid; grid-template-columns: 3.4ch 1fr; gap: 12px; align-items: baseline; }
.mods dt { font: 800 1.15rem var(--display); }
.mods dd { margin: 0; color: var(--ink-2); }
.pad-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 8px 14px; }
.pad-row { display: grid; grid-template-columns: repeat(3, 1fr); gap: 6px; }
.chip-btn {
  border: 1.5px solid var(--ink); background: var(--card); border-radius: 10px; padding: 8px 0;
  font: 800 1rem var(--display); transition: background 0.1s ease;
}
.chip-btn:hover { background: var(--yellow); }
.chip-btn:active { transform: translateY(1px); }
.pad-sub { margin: 14px 0 8px; color: var(--ink-2); font-size: 0.92rem; }
.pad-desc { min-height: 3.2em; padding: 12px 14px; border-left: 4px solid var(--yellow); background: var(--paper-2); border-radius: 0 10px 10px 0; }

/* ---------- automatic solve ---------- */
.solver-bar { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; }
.btn-stop { background: var(--card); box-shadow: none; }
.btn:disabled, .chip-btn:disabled, .seg button:disabled { opacity: 0.45; cursor: not-allowed; transform: none; }
.chip-btn:disabled:hover { background: var(--card); }
.solver { display: grid; gap: 12px; padding: 16px; background: var(--card); border: 1.5px solid var(--line); border-radius: 18px; }
.sv-head { display: flex; justify-content: space-between; align-items: baseline; gap: 12px; }
.sv-head strong { font: 800 1.25rem/1.15 var(--display); }
.sv-head span { color: var(--ink-2); font-size: 0.9rem; font-variant-numeric: tabular-nums; }
.sv-label { font-weight: 700; }
.solver .alg { padding: 0; border: 0; }
.sv-steps { list-style: none; margin: 0; padding: 10px 0 0; display: grid; gap: 2px; border-top: 1px solid var(--line); }
.sv-step { display: grid; grid-template-columns: 1.8rem 1fr; gap: 10px; align-items: start; padding: 6px 4px; border-radius: 10px; }
.sv-step div { display: grid; }
.sv-step strong { font: 700 0.98rem var(--display); }
.sv-step small { color: var(--ink-2); font-size: 0.85rem; line-height: 1.35; }
.sv-dot { display: grid; place-items: center; width: 1.6rem; height: 1.6rem; border-radius: 8px; border: 1.5px solid var(--ink); font: 800 0.8rem var(--display); }
.sv-step.current { background: var(--paper-2); }
.sv-step.current .sv-dot { background: var(--yellow); }
.sv-step.ok .sv-dot { background: var(--ink); color: #fff; }
.sv-step.skipped strong { color: var(--ink-2); }
.sv-step.skipped .sv-dot { border-style: dashed; color: var(--ink-2); }
.sv-status {
  width: fit-content; padding: 4px 12px; border-radius: 999px; border: 1.5px solid var(--ink);
  background: var(--paper-2); font-weight: 700; font-size: 0.92rem;
}
.sv-extra { display: flex; flex-wrap: wrap; gap: 8px; }
/* A long quick solution scrolls inside its own box; offsetTop is measured from it. */
.sv-alg.long { position: relative; max-height: 11.5rem; overflow-y: auto; overscroll-behavior: contain; }
.chip-hold { border-style: dashed; border-color: var(--ink-2); color: var(--ink); background: var(--card); font-size: 0.98rem; }
.chip-hold.now { border-style: solid; }
.cap-sub { font: 500 0.92rem/1.35 var(--body); color: var(--ink-2); }

/* A sticky column taller than the screen hides its bottom: release it while
   the narration panel is open. */
.stage-col:has(.solver:not([hidden])) { position: relative; top: 0; }
.auto-host { display: grid; gap: 12px; }
/* While solving, the locked player only gets in the way of the narration. */
.stage-col.auto-on .player { display: none; }
.stage { scroll-margin-top: 84px; }
@media (max-width: 600px) {
  .solver { padding: 12px; }
  .solver-bar .btn { flex: 1 1 100%; justify-content: center; }
  .solver-bar .speed { width: 100%; justify-content: space-between; }
  .solver-bar .speed button { flex: 1; }
  .sv-head { flex-wrap: wrap; }
  .solver .chip { font-size: 0.95rem; padding: 5px 7px; }
  .stage { scroll-margin-top: 112px; }
  .cap-label { font-size: 1.02rem; max-width: none; }
  .cap-step { font-size: 0.8rem; }
  .stage-cap { font-size: 0.92rem; }
}


/* ---------- editor ---------- */
.editor-grid { display: grid; grid-template-columns: minmax(0, 1.05fr) minmax(320px, 0.95fr); gap: 28px; align-items: start; }
.ed-col { display: grid; gap: 16px; min-width: 0; }
.ed-top { display: flex; flex-wrap: wrap; align-items: center; gap: 10px 14px; }
.chip-note { display: inline-flex; align-items: center; gap: 6px; padding: 5px 12px; border-radius: 999px; background: var(--card); border: 1.5px solid var(--line); font-weight: 700; font-size: 0.88rem; }
.net-wrap { container-type: inline-size; }
.net {
  display: grid; gap: 8px; justify-content: center;
  grid-template-columns: repeat(2, auto);
  grid-template-areas: "U F" "R B" "D L";
  --s: clamp(32px, calc((100cqw - 40px) / (var(--n) * 2)), 56px);
}
.net-face { display: grid; gap: 4px; justify-items: start; padding: 6px; border-radius: 12px; background: rgba(21, 25, 58, 0.07); }
.net-name { font: 700 0.78rem var(--body); color: var(--ink-2); }
.net-cells { display: grid; grid-template-columns: repeat(var(--n), var(--s)); gap: 3px; }
.stk {
  display: block; width: var(--s); height: var(--s); padding: 0; border-radius: 7px;
  border: 1.5px solid rgba(21, 25, 58, 0.5); background: var(--c, #59607C); touch-action: manipulation;
}
button.stk:hover { transform: scale(1.06); }
.stk.empty { background: repeating-linear-gradient(45deg, #6B7290 0 4px, #59607C 4px 8px); }
.stk.fixed { cursor: default; box-shadow: inset 0 0 0 3px rgba(255, 255, 255, 0.4); }
.stk.bad { outline: 3px solid var(--red); outline-offset: 1px; position: relative; z-index: 1; }
.stk:disabled { cursor: not-allowed; }
@container (min-width: 440px) {
  .net[data-n="3"] {
    grid-template-columns: repeat(4, auto);
    grid-template-areas: ". U . ." "L F R B" ". D . .";
    --s: clamp(32px, calc((100cqw - 70px) / (var(--n) * 4)), 52px);
  }
}
@container (min-width: 590px) {
  .net[data-n="4"] {
    grid-template-columns: repeat(4, auto);
    grid-template-areas: ". U . ." "L F R B" ". D . .";
    --s: clamp(32px, calc((100cqw - 70px) / (var(--n) * 4)), 52px);
  }
}
.palette { display: flex; flex-wrap: wrap; gap: 8px; }
.pal {
  display: inline-flex; align-items: center; gap: 8px; min-height: 40px; padding: 6px 14px;
  border-radius: 999px; border: 1.5px solid var(--line); background: var(--card); font-weight: 700; font-size: 0.95rem;
}
.pal[aria-checked="true"] { border-color: var(--ink); background: var(--ink); color: #fff; }
.pal:disabled { opacity: 0.45; cursor: not-allowed; }
.ed-status { width: fit-content; padding: 4px 12px; border-radius: 999px; font-weight: 700; font-size: 0.92rem; border: 1.5px solid var(--ink); background: var(--paper-2); }
.ed-status[data-state="ok"] { background: #CFEFDD; }
.ed-status[data-state="bad"] { background: #F8D3D9; }
.ed-msgs { list-style: none; margin: 0; padding: 0; display: grid; gap: 6px; }
.ed-msgs:empty { display: none; }
.ed-msgs li { padding: 8px 12px; background: var(--card); border-left: 4px solid var(--red); border-radius: 0 10px 10px 0; font-size: 0.97rem; }
.ed-msgs li.ok { border-left-color: var(--green); }
.ed-actions { display: flex; flex-wrap: wrap; gap: 8px; }
@media (max-width: 980px) { .editor-grid { grid-template-columns: 1fr; } }

/* ---------- guide ---------- */
.guide-head { max-width: 80ch; }
.guide-grid { display: grid; grid-template-columns: minmax(0, 1.3fr) minmax(330px, 0.85fr); gap: 28px; align-items: start; }
.stage-col { position: sticky; top: 76px; display: grid; gap: 14px; }
.stage-guide { height: min(58vh, 560px); }
.guide-cap { right: 140px; display: grid; gap: 4px; }
.cap-step { font: 500 0.9rem var(--body); color: var(--ink-2); }
.cap-label { font: 800 clamp(1.15rem, 2vw, 1.5rem)/1.15 var(--display); letter-spacing: -0.01em; max-width: 26ch; }
.player { display: grid; gap: 12px; }
.cases { display: flex; flex-wrap: wrap; gap: 6px; }
.cases button {
  border: 1.5px solid var(--line); background: var(--paper-2); border-radius: 999px;
  padding: 6px 14px; font-weight: 700; font-size: 0.92rem;
}
.cases button[aria-selected="true"] { border-color: var(--ink); background: var(--ink); color: #fff; }
.alg {
  display: flex; flex-wrap: wrap; gap: 10px 14px; padding: 14px;
  background: var(--card); border: 1.5px solid var(--line); border-radius: 18px;
}
.group { display: grid; gap: 6px; align-content: start; }
.chips { display: flex; flex-wrap: wrap; gap: 5px; padding-bottom: 6px; border-bottom: 3px solid var(--line); transition: border-color 0.2s ease; }
.group.active .chips { border-bottom-color: var(--ink); }
.glabel { font-size: 0.8rem; color: var(--ink-2); max-width: 22ch; line-height: 1.3; }
.group.active .glabel { color: var(--ink); font-weight: 700; }
.chip {
  min-width: 2.6ch; padding: 6px 9px; border-radius: 9px; border: 1.5px solid var(--line);
  background: var(--paper-2); font: 800 1.08rem/1.1 var(--display); color: var(--ink-2);
  transition: background 0.15s ease, color 0.15s ease, transform 0.15s ease;
}
.chip.next { border-color: var(--ink); color: var(--ink); background: var(--card); }
.chip.now { background: var(--yellow); border-color: var(--ink); color: var(--ink); transform: translateY(-2px); box-shadow: 0 2px 0 var(--ink); }
.chip.done { background: var(--ink); border-color: var(--ink); color: #fff; }
.controls { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; }
.icon-btn {
  display: grid; place-items: center; width: 44px; height: 44px; border-radius: 50%;
  border: 1.5px solid var(--ink); background: var(--card);
}
.icon-btn:hover { background: var(--paper-2); }
.icon-btn-main { width: 54px; height: 54px; background: var(--yellow); box-shadow: 0 3px 0 var(--ink); }
.icon-btn-main:hover { background: #FFDC4D; }
.speed { margin-left: 6px; }
.count { margin-left: auto; color: var(--ink-2); font-size: 0.92rem; font-variant-numeric: tabular-nums; }

.steps { list-style: none; margin: 0; padding: 0; display: grid; gap: 0; border-top: 2px solid var(--ink); }
.step { border-bottom: 1px solid var(--line); }
.step-head {
  width: 100%; display: grid; grid-template-columns: 2.4rem 1fr auto; align-items: center; gap: 12px;
  padding: 14px 4px; border: 0; background: transparent; text-align: left;
}
.step-num {
  display: grid; place-items: center; width: 2.2rem; height: 2.2rem; border-radius: 10px;
  border: 1.5px solid var(--ink); font: 800 1rem var(--display);
}
.step.open .step-num { background: var(--ink); color: #fff; }
.step-title { font: 700 1.12rem/1.2 var(--display); }
.step-done { color: var(--green); }
.step-head:hover .step-title { text-decoration: underline; text-underline-offset: 4px; }
.step-body { padding: 0 4px 22px 3.4rem; display: grid; gap: 14px; }
.goal { font-weight: 700; font-size: 1.08rem; }
.how { margin: 0; padding-left: 1.2rem; display: grid; gap: 8px; }
.how li::marker { font-weight: 700; color: var(--ink-2); }
.tip { padding: 10px 14px; background: var(--paper-2); border-left: 4px solid var(--yellow); border-radius: 0 10px 10px 0; font-size: 0.97rem; }
.step-foot { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: center; gap: 10px; }
.master { display: inline-flex; align-items: center; gap: 8px; font-weight: 700; font-size: 0.95rem; cursor: pointer; }
.master input { width: 18px; height: 18px; accent-color: var(--green); }

/* ---------- why ---------- */
.why-block {
  display: grid; grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr); gap: clamp(24px, 4vw, 56px);
  align-items: center; padding: 48px 0; border-top: 1px solid var(--line);
}
.why-block-rev > .stage { order: -1; }
.why-text { display: grid; gap: 14px; max-width: 58ch; align-content: start; }
.why-text p { color: var(--ink-2); }
.why-text .btn { width: fit-content; }
.fine { font-size: 0.88rem; }
.stage-why { height: min(56vh, 480px); }
.stage-dual { height: min(52vh, 440px); }
.units { display: grid; gap: 22px; }
.unit-head { display: flex; justify-content: space-between; align-items: baseline; margin-bottom: 8px; }
.unit-head strong { font: 700 1.05rem var(--display); }
.unit-count { font: 800 1.7rem/1 var(--display); font-variant-numeric: tabular-nums; }
.unit-grid { display: grid; grid-template-columns: repeat(var(--cols), 1fr); grid-auto-flow: column; grid-template-rows: repeat(3, auto); gap: 3px; width: 100%; }
.unit-grid i { aspect-ratio: 1; border-radius: 3px; background: var(--ink-2); opacity: 0.5; }
.unit-grid i.lit { background: var(--yellow); opacity: 1; box-shadow: inset 0 0 0 1.5px var(--ink); }
.unit-note { margin-top: 6px; color: var(--ink-2); font-size: 0.9rem; }
.ladder { display: grid; gap: 10px; }
.rung { display: grid; grid-template-columns: minmax(0, 1.4fr) minmax(24px, 0.6fr) 6.5rem; align-items: center; gap: 10px; }
.rung-steps { display: flex; flex-wrap: wrap; gap: 6px; justify-content: flex-end; }
.rung-steps span { padding: 6px 12px; border-radius: 10px; background: var(--card); border: 1.5px solid var(--line); font-weight: 700; font-size: 0.93rem; }
.rung-line { height: 3px; background: var(--lc); border-radius: 2px; position: relative; }
.rung-line::after { content: ''; position: absolute; right: -2px; top: -5px; border: 6.5px solid transparent; border-left: 9px solid var(--lc); border-right: 0; }
.rung-phase {
  padding: 10px 0; border-radius: 12px; text-align: center; font: 800 1.15rem var(--display);
  background: var(--c); color: var(--ink); box-shadow: inset 0 0 0 2px rgba(21,25,58,0.25);
}
.ladder-cap { display: grid; grid-template-columns: minmax(0, 1.4fr) minmax(24px, 0.6fr) 6.5rem; gap: 10px; color: var(--ink-2); font-size: 0.88rem; font-weight: 700; }
.ladder-cap span:first-child { text-align: right; }
.ladder-cap span:last-child { grid-column: 3; text-align: center; }
.parity-fig { margin: 0; display: grid; gap: 10px; }
.parity-caps { display: grid; grid-template-columns: 1fr 1fr; text-align: center; font-weight: 700; font-size: 0.95rem; }

/* ---------- responsive ---------- */
@media (max-width: 980px) {
  .hero { grid-template-columns: 1fr; min-height: 0; padding-top: 20px; }
  .hero-stage { height: 52vh; order: -1; }
  .route-list { grid-template-columns: 1fr 1fr; }
  .route-list li:nth-child(2) { border-right: 0; }
  .route-list li { border-bottom: 1px solid var(--line); }
  .route-list li:nth-child(3) a { margin-left: 0; }
  .split, .guide-grid, .why-block { grid-template-columns: 1fr; }
  .why-block-rev > .stage { order: 0; }
  .stage-tall { position: relative; top: 0; height: 52vh; }
  .stage-col { position: relative; top: 0; }
  .stage-guide { height: 50vh; }
}
@media (max-width: 600px) {
  body { font-size: 1rem; }
  .topbar { flex-wrap: wrap; padding-block: 10px; gap: 8px; }
  .nav { width: 100%; justify-content: space-between; }
  .nav a { padding: 6px 10px; }
  .route-list { grid-template-columns: 1fr; }
  .route-list li { border-right: 0; }
  .route-list a { margin-left: 0; }
  .faces { grid-template-columns: 1fr; }
  .pad-grid { grid-template-columns: 1fr; }
  .stage-cap { right: 16px; top: 54px; }
  .guide-cap { right: 16px; }
  .stage-reset { top: 10px; }
  .hold-legend { font-size: 0.78rem; }
  .step-body { padding-left: 4px; }
  .count { width: 100%; margin-left: 0; }
  .rung { grid-template-columns: minmax(0, 1fr) 20px 4.6rem; }
  .ladder-cap { grid-template-columns: minmax(0, 1fr) 20px 4.6rem; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition: none !important; animation: none !important; scroll-behavior: auto !important; }
}