/* ---------------------------------------------------------------- tokens */
:root {
  --bg:        #0a0c10;
  --bg-2:      #0f1319;
  --panel:     #131820;
  --panel-2:   #171d27;
  --line:      #232b38;
  --line-2:    #2e3948;
  --ink:       #e8edf5;
  --ink-2:     #a3b0c2;
  --ink-3:     #6b7889;
  --accent:    #5ac8fa;
  --accent-2:  #7ee0c0;
  --warn:      #ffb454;
  --radius:    14px;
  --mono: ui-monospace, "SF Mono", SFMono-Regular, "JetBrains Mono", Menlo, Consolas, monospace;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Inter, system-ui, sans-serif;
  --maxw: 1240px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  background-image:
    radial-gradient(1100px 620px at 78% -12%, rgba(90,200,250,.10), transparent 60%),
    radial-gradient(900px 520px at 8% 8%, rgba(126,224,192,.06), transparent 62%);
  background-attachment: fixed;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

/* --------------------------------------------------------------- topbar */
.topbar {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; justify-content: space-between;
  gap: 24px;
  padding: 14px max(20px, 4vw);
  background: rgba(10,12,16,.72);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--line);
}
.wordmark {
  font-family: var(--mono);
  font-size: 15px; letter-spacing: .02em;
  color: var(--ink); text-decoration: none;
  display: inline-flex; align-items: center; gap: 7px;
}
.wordmark:hover { text-decoration: none; }
.wm-arrow { color: var(--accent); }
.wm-b { color: var(--ink); font-weight: 600; }
.topbar nav { display: flex; gap: 22px; font-size: 14px; }
.topbar nav a { color: var(--ink-2); }
.topbar nav a:hover { color: var(--ink); text-decoration: none; }

/* ----------------------------------------------------------------- hero */
.hero {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: clamp(48px, 8vw, 104px) max(20px, 4vw) clamp(40px, 6vw, 72px);
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: clamp(28px, 4vw, 60px);
  align-items: center;
}
.eyebrow {
  font-family: var(--mono); font-size: 12.5px; letter-spacing: .06em;
  text-transform: uppercase; color: var(--ink-3); margin: 0 0 18px;
}
.hero h1 {
  font-size: clamp(38px, 5.4vw, 68px);
  line-height: 1.04;
  letter-spacing: -.025em;
  margin: 0 0 22px;
  font-weight: 650;
}
.hero h1 em {
  font-style: normal;
  background: linear-gradient(100deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.lede { font-size: 17.5px; color: var(--ink-2); margin: 0 0 16px; max-width: 56ch; }
.lede-sub { font-size: 15.5px; color: var(--ink-3); margin: 0 0 30px; max-width: 56ch; }
.hero-cta { display: flex; gap: 12px; flex-wrap: wrap; }

.btn {
  display: inline-block;
  padding: 11px 20px;
  border-radius: 10px;
  border: 1px solid var(--line-2);
  color: var(--ink);
  font-size: 14.5px; font-weight: 500;
  background: var(--panel);
  transition: border-color .15s, background .15s, transform .15s;
}
.btn:hover { text-decoration: none; border-color: var(--ink-3); transform: translateY(-1px); }
.btn-primary {
  background: linear-gradient(180deg, #6fd2fb, #38b6ee);
  border-color: transparent; color: #04202c; font-weight: 620;
}
.btn-primary:hover { filter: brightness(1.06); }

.hero-stage { display: flex; flex-direction: column; gap: 10px; }
.hero-stage .viewer { height: clamp(320px, 42vw, 460px); }
.hero-caption {
  font-family: var(--mono); font-size: 11.5px; color: var(--ink-3);
  display: flex; align-items: center; gap: 8px; justify-content: flex-end;
}
.dot {
  width: 7px; height: 7px; border-radius: 50%;
  background: var(--accent-2); box-shadow: 0 0 0 0 rgba(126,224,192,.6);
  animation: pulse 2.4s infinite;
}
@keyframes pulse {
  0%   { box-shadow: 0 0 0 0 rgba(126,224,192,.5); }
  70%  { box-shadow: 0 0 0 8px rgba(126,224,192,0); }
  100% { box-shadow: 0 0 0 0 rgba(126,224,192,0); }
}

/* --------------------------------------------------------------- viewer */
.viewer {
  position: relative;
  width: 100%;
  border-radius: var(--radius);
  border: 1px solid var(--line);
  background:
    linear-gradient(180deg, #12171f 0%, #0c1015 100%);
  overflow: hidden;
  touch-action: pan-y;
}
.viewer canvas { display: block; width: 100%; height: 100%; }
.viewer::after {
  /* faint blueprint grid */
  content: "";
  position: absolute; inset: 0; pointer-events: none;
  background-image:
    linear-gradient(rgba(120,150,180,.05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(120,150,180,.05) 1px, transparent 1px);
  background-size: 34px 34px;
  mask-image: radial-gradient(circle at 50% 55%, transparent 30%, #000 85%);
  -webkit-mask-image: radial-gradient(circle at 50% 55%, transparent 30%, #000 85%);
}
.viewer .v-loading {
  position: absolute; inset: 0;
  display: grid; place-items: center;
  font-family: var(--mono); font-size: 12px; color: var(--ink-3);
  z-index: 3;
}
.viewer .v-hint {
  position: absolute; left: 12px; bottom: 11px; z-index: 3;
  font-family: var(--mono); font-size: 11px; color: var(--ink-3);
  opacity: .85; pointer-events: none;
  transition: opacity .4s;
}
.viewer.touched .v-hint { opacity: 0; }
.v-tools {
  position: absolute; right: 10px; top: 10px; z-index: 4;
  display: flex; gap: 6px;
}
.v-tools button {
  font-family: var(--mono); font-size: 11px;
  color: var(--ink-2);
  background: rgba(12,16,21,.78);
  border: 1px solid var(--line-2);
  border-radius: 8px;
  padding: 5px 9px;
  cursor: pointer;
  transition: color .15s, border-color .15s, background .15s;
}
.v-tools button:hover { color: var(--ink); border-color: var(--ink-3); }
.v-tools button[aria-pressed="true"] {
  color: #04202c; background: var(--accent); border-color: transparent; font-weight: 600;
}

/* --------------------------------------------------------------- ladder */
.ladder { max-width: var(--maxw); margin: 0 auto; padding: 0 max(20px, 4vw) 40px; }

.card {
  border-top: 1px solid var(--line);
  padding: clamp(44px, 6vw, 78px) 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.12fr);
  gap: clamp(28px, 4vw, 56px);
  align-items: start;
}
.card-info { min-width: 0; }
.card-stage { min-width: 0; position: sticky; top: 78px; }
.card-stage .viewer { height: clamp(340px, 44vw, 520px); }

.card-num {
  font-family: var(--mono); font-size: 12px; letter-spacing: .12em;
  color: var(--ink-3); text-transform: uppercase;
  display: flex; align-items: center; gap: 10px; margin-bottom: 14px;
}
.card-num .rung {
  flex: 1; height: 1px;
  background: linear-gradient(90deg, var(--line-2), transparent);
}
.card h2 {
  font-size: clamp(27px, 3.1vw, 38px);
  letter-spacing: -.02em; line-height: 1.12;
  margin: 0 0 18px; font-weight: 640;
}

.prompt {
  display: flex; gap: 11px; align-items: flex-start;
  background: var(--panel);
  border: 1px solid var(--line);
  border-left: 2px solid var(--accent);
  border-radius: 10px;
  padding: 13px 15px;
  margin: 0 0 20px;
}
.prompt .chev { color: var(--accent); font-family: var(--mono); font-size: 14px; line-height: 1.5; }
.prompt p { margin: 0; font-family: var(--mono); font-size: 13.5px; color: var(--ink); line-height: 1.55; }

.blurb { color: var(--ink-2); font-size: 15.5px; margin: 0 0 24px; max-width: 58ch; }

/* facts */
.bbox {
  display: flex; align-items: baseline; justify-content: space-between; gap: 14px;
  background: var(--panel); border: 1px solid var(--line);
  border-radius: 10px 10px 0 0; border-bottom: 0;
  padding: 11px 13px;
}
.bbox span {
  font-family: var(--mono); font-size: 10.5px; letter-spacing: .06em;
  text-transform: uppercase; color: var(--ink-3);
}
.bbox b { font-family: var(--mono); font-size: 14.5px; font-weight: 500; color: var(--ink); }
.bbox + .facts { border-radius: 0 0 10px 10px; }

.facts {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: 10px;
  overflow: hidden;
  margin-bottom: 24px;
}
.fact { background: var(--panel); padding: 11px 13px; }
.fact dt {
  font-family: var(--mono); font-size: 10.5px; letter-spacing: .06em;
  text-transform: uppercase; color: var(--ink-3); margin: 0 0 4px;
}
.fact dd { margin: 0; font-family: var(--mono); font-size: 14.5px; color: var(--ink); }
.fact dd small { color: var(--ink-3); font-size: 11px; }

/* parameter slider */
.param {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 15px 16px 17px;
  margin-bottom: 22px;
}
.param-head {
  display: flex; align-items: baseline; justify-content: space-between;
  gap: 12px; margin-bottom: 4px;
}
.param-label { font-size: 13.5px; color: var(--ink-2); }
.param-val { font-family: var(--mono); font-size: 15px; color: var(--accent); font-weight: 600; }
.param-code {
  font-family: var(--mono); font-size: 11.5px; color: var(--ink-3);
  margin: 0 0 11px; overflow-x: auto; white-space: nowrap;
}
.param input[type=range] {
  width: 100%; margin: 0; accent-color: var(--accent);
  height: 22px; cursor: pointer;
}
.param-foot {
  font-family: var(--mono); font-size: 10.5px; color: var(--ink-3);
  margin-top: 8px; display: flex; justify-content: space-between;
}

/* downloads */
.dl { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 20px; }
.dl a {
  font-family: var(--mono); font-size: 12px;
  color: var(--ink-2);
  border: 1px solid var(--line-2); border-radius: 8px;
  padding: 6px 11px;
  transition: color .15s, border-color .15s;
}
.dl a:hover { color: var(--ink); border-color: var(--ink-3); text-decoration: none; }
.dl a b { color: var(--accent); font-weight: 600; }
.dl a span { color: var(--ink-3); }

/* code */
details.code {
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--panel);
  overflow: hidden;
}
details.code > summary {
  cursor: pointer; list-style: none;
  padding: 12px 15px;
  font-family: var(--mono); font-size: 12.5px; color: var(--ink-2);
  display: flex; align-items: center; justify-content: space-between; gap: 10px;
}
details.code > summary::-webkit-details-marker { display: none; }
details.code > summary:hover { color: var(--ink); }
details.code > summary .tw { color: var(--ink-3); font-size: 11px; }
details.code[open] > summary { border-bottom: 1px solid var(--line); }
details.code pre {
  margin: 0; padding: 15px;
  overflow-x: auto;
  font-family: var(--mono); font-size: 12.5px; line-height: 1.65;
  background: #0c1015;
  max-height: 460px;
}
.tok-kw   { color: #ff8ec7; }
.tok-str  { color: #9ee493; }
.tok-num  { color: var(--warn); }
.tok-com  { color: #5d6b7d; font-style: italic; }
.tok-fn   { color: #7ecbff; }
.tok-dec  { color: #c4a2ff; }

/* ------------------------------------------------------------------ how */
.how {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: clamp(48px, 7vw, 90px) max(20px, 4vw);
  border-top: 1px solid var(--line);
}
.how h2 {
  font-size: clamp(26px, 3vw, 36px); letter-spacing: -.02em;
  margin: 0 0 32px; font-weight: 640;
}
.how-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 18px; margin-bottom: 44px;
}
.how-grid article {
  background: var(--panel); border: 1px solid var(--line);
  border-radius: 12px; padding: 20px;
}
.how-grid h3 {
  font-family: var(--mono); font-size: 12.5px; letter-spacing: .04em;
  color: var(--accent); margin: 0 0 10px; font-weight: 600;
}
.how-grid p { margin: 0; font-size: 14.5px; color: var(--ink-2); }

.why {
  border-left: 2px solid var(--accent-2);
  padding: 4px 0 4px 22px;
  max-width: 74ch;
}
.why h3 { font-size: 20px; margin: 0 0 12px; font-weight: 620; }
.why p { color: var(--ink-2); font-size: 15.5px; margin: 0 0 14px; }
.why em { color: var(--ink); font-style: italic; }

/* --------------------------------------------------------------- footer */
footer { border-top: 1px solid var(--line); }
.foot-inner {
  max-width: var(--maxw); margin: 0 auto;
  padding: 30px max(20px, 4vw) 54px;
  display: flex; flex-wrap: wrap; gap: 14px;
  justify-content: space-between; align-items: baseline;
}
.foot-inner p { margin: 0; font-size: 13.5px; color: var(--ink-3); max-width: 62ch; }
.foot-meta { font-family: var(--mono); font-size: 11.5px; }

/* -------------------------------------------------------------- responsive */
@media (max-width: 940px) {
  .hero { grid-template-columns: 1fr; }
  .hero-stage { order: -1; }
  .card { grid-template-columns: 1fr; }
  .card-stage { position: static; order: -1; }
  .card-stage .viewer { height: clamp(280px, 62vw, 400px); }
  .hero-caption { justify-content: flex-start; }
}
@media (max-width: 560px) {
  .topbar nav { gap: 14px; font-size: 13px; }
  .topbar nav a:nth-child(2) { display: none; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .dot { animation: none; }
}