:root {
  --bg: #0b1017;
  --bg-raised: #111923;
  --bg-soft: #151f2a;
  --ink: #f1eee7;
  --muted: #a3adb8;
  --dim: #697786;
  --line: #273441;
  --line-bright: #3b4b5c;
  --cyan: #7be1dd;
  --cyan-deep: #173c41;
  --amber: #e8b86d;
  --amber-soft: #3e3020;
  --max: 1180px;
  --pad: clamp(1.25rem, 3.5vw, 4.5rem);
  --serif: Georgia, "Times New Roman", serif;
  --sans: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --mono: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; background: var(--bg); }
body { margin: 0; color: var(--ink); background: var(--bg); font-family: var(--sans); font-size: 16px; line-height: 1.55; }
a { color: inherit; }
button { font: inherit; }

:focus-visible { outline: 2px solid var(--cyan); outline-offset: 4px; }
.skip-link { position: fixed; z-index: 20; top: .75rem; left: .75rem; padding: .65rem .9rem; color: var(--bg); background: var(--cyan); transform: translateY(-160%); transition: transform .2s ease; }
.skip-link:focus { transform: translateY(0); }
.section-shell { width: min(100%, var(--max)); margin: 0 auto; padding-inline: var(--pad); }

.site-header { border-bottom: 1px solid var(--line); }
.header-inner { width: min(100%, var(--max)); min-height: 72px; margin: 0 auto; padding: 0 var(--pad); display: flex; align-items: center; justify-content: space-between; gap: 1rem; }
.wordmark { display: inline-flex; align-items: center; gap: .7rem; color: var(--ink); text-decoration: none; font: 700 .75rem/1 var(--mono); letter-spacing: .12em; }
.wordmark-mark { display: grid; width: 26px; height: 26px; place-items: center; color: var(--bg); background: var(--cyan); font: 700 .8rem/1 var(--serif); letter-spacing: 0; }
.wordmark em { color: var(--cyan); font-style: normal; }
.header-note { color: var(--dim); font: 500 .65rem/1 var(--mono); letter-spacing: .08em; }

.site-nav { position: sticky; z-index: 10; top: 0; border-bottom: 1px solid var(--line); background: rgba(11, 16, 23, .94); backdrop-filter: blur(12px); }
.nav-inner { width: min(100%, var(--max)); margin: 0 auto; padding: 0 var(--pad); display: flex; gap: clamp(1rem, 3vw, 3rem); overflow-x: auto; scrollbar-width: none; }
.nav-inner::-webkit-scrollbar { display: none; }
.nav-link { position: relative; display: inline-flex; flex: 0 0 auto; align-items: center; gap: .65rem; min-height: 52px; color: var(--dim); text-decoration: none; font: 600 .68rem/1 var(--mono); letter-spacing: .035em; text-transform: uppercase; transition: color .2s ease; }
.nav-link span { color: var(--line-bright); }
.nav-link:hover, .nav-link.is-active { color: var(--ink); }
.nav-link.is-active span { color: var(--cyan); }
.nav-link.is-active::after { position: absolute; right: 0; bottom: -1px; left: 0; height: 2px; background: var(--cyan); content: ""; }

.hero { min-height: 560px; padding-top: clamp(4rem, 9vw, 8rem); padding-bottom: clamp(4rem, 8vw, 7rem); display: grid; grid-template-columns: minmax(0, 1.25fr) minmax(270px, .75fr); align-items: end; gap: clamp(3rem, 8vw, 8rem); }
.eyebrow { margin: 0 0 1.2rem; color: var(--cyan); font: 600 .68rem/1.2 var(--mono); letter-spacing: .12em; text-transform: uppercase; }
.eyebrow-dot { display: inline-block; width: 7px; height: 7px; margin-right: .5rem; border-radius: 50%; background: var(--cyan); box-shadow: 0 0 0 4px rgba(123,225,221,.12); vertical-align: 1px; }
h1, h2, h3, p { margin-top: 0; }
h1 { max-width: 740px; margin-bottom: 1.5rem; font: 400 clamp(3.8rem, 8vw, 7.6rem)/.89 var(--serif); letter-spacing: -.065em; }
h1 span { color: var(--cyan); }
.hero-lede { max-width: 570px; margin-bottom: 2.2rem; color: var(--muted); font-size: clamp(1rem, 1.5vw, 1.2rem); line-height: 1.6; }
.hero-actions { display: flex; align-items: center; flex-wrap: wrap; gap: 1.35rem; }
.button { display: inline-flex; align-items: center; gap: 1rem; padding: .85rem 1.1rem; text-decoration: none; font: 700 .72rem/1 var(--mono); letter-spacing: .04em; text-transform: uppercase; }
.button-primary { color: var(--bg); background: var(--cyan); }
.button-primary:hover { background: var(--ink); }
.text-link { color: var(--muted); text-decoration: none; font-size: .88rem; }
.text-link:hover { color: var(--cyan); }
.current-card { position: relative; padding: 1.5rem; border: 1px solid var(--line-bright); background: var(--bg-raised); }
.current-card::before { position: absolute; top: -1px; left: -1px; width: 42px; height: 4px; background: var(--cyan); content: ""; }
.card-kicker { display: flex; justify-content: space-between; gap: .5rem; color: var(--cyan); font: 600 .63rem/1 var(--mono); letter-spacing: .1em; }
.card-kicker span { color: var(--dim); }
.current-card h2 { margin: 4.4rem 0 1rem; font: 400 clamp(2.2rem, 4vw, 3.6rem)/.95 var(--serif); letter-spacing: -.05em; }
.current-card p { max-width: 260px; margin-bottom: 3rem; color: var(--muted); font-size: .91rem; }
.current-card-foot { display: flex; align-items: center; gap: .55rem; color: var(--ink); font: 600 .65rem/1 var(--mono); letter-spacing: .05em; text-transform: uppercase; }
.status-pip { width: 7px; height: 7px; border-radius: 50%; background: var(--cyan); }

.snapshot-strip { display: grid; grid-template-columns: 1fr 1px 1fr 1px 1.7fr; align-items: center; padding-top: 1.5rem; padding-bottom: 1.5rem; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.snapshot-item { display: flex; align-items: baseline; gap: 1rem; padding-inline: 1.5rem; }
.snapshot-item:first-child { padding-left: 0; }
.snapshot-value { color: var(--cyan); font: 400 clamp(2rem, 4vw, 3.5rem)/1 var(--serif); letter-spacing: -.06em; }
.snapshot-word { font-size: clamp(1.35rem, 2.6vw, 2.2rem); }
.snapshot-label { color: var(--ink); font-size: .78rem; line-height: 1.35; }
.snapshot-label small { color: var(--dim); font-size: .69rem; }
.snapshot-divider { width: 1px; height: 38px; background: var(--line); }

.section-block { padding-top: clamp(5rem, 10vw, 9rem); padding-bottom: clamp(5rem, 10vw, 9rem); }
.section-heading { display: grid; grid-template-columns: minmax(0, 1fr) minmax(240px, .55fr); align-items: end; gap: 3rem; margin-bottom: 3rem; }
.section-heading h2 { margin-bottom: 0; font: 400 clamp(2.6rem, 5vw, 5rem)/.92 var(--serif); letter-spacing: -.06em; }
.section-intro { max-width: 355px; margin-bottom: .25rem; color: var(--muted); font-size: .95rem; }

.phase-list { border-top: 1px solid var(--line); }
.phase-card { border-bottom: 1px solid var(--line); }
.phase-card.is-open .phase-number { color: var(--cyan); }
.phase-card.is-open .phase-symbol { border-color: var(--cyan); }
.phase-toggle { width: 100%; padding: 1.2rem 0; color: var(--ink); border: 0; background: transparent; display: grid; grid-template-columns: 74px minmax(0, 1fr) 38px; align-items: center; gap: 1rem; text-align: left; cursor: pointer; }
.phase-toggle:hover .phase-title { color: var(--cyan); }
.phase-number { color: var(--dim); font: 400 1.6rem/1 var(--serif); letter-spacing: -.05em; }
.phase-heading { display: flex; flex-wrap: wrap; align-items: baseline; gap: .9rem; }
.phase-status { color: var(--cyan); font: 600 .62rem/1 var(--mono); letter-spacing: .09em; }
.phase-card[data-phase-id="graphs-dp"] .phase-status, .phase-card[data-phase-id="binary-search"] .phase-status { color: var(--amber); }
.phase-title { font: 400 clamp(1.35rem, 2.5vw, 2.25rem)/1.1 var(--serif); letter-spacing: -.035em; transition: color .2s ease; }
.phase-symbol { display: grid; width: 32px; height: 32px; place-items: center; color: var(--cyan); border: 1px solid var(--line-bright); font: 400 1.15rem/1 var(--sans); }
.phase-panel { padding: 0 74px 2.8rem; color: var(--muted); }
.phase-panel > p { max-width: 680px; margin-bottom: 2rem; font-size: 1rem; }
.phase-columns { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 1.5rem 4rem; }
.phase-panel h3 { margin-bottom: .7rem; color: var(--ink); font: 700 .65rem/1 var(--mono); letter-spacing: .1em; text-transform: uppercase; }
.phase-panel .subheading { margin-top: 1.7rem; }
.phase-panel p { max-width: 500px; font-size: .9rem; }
.gate { padding: 1.2rem 1.3rem; border-left: 2px solid var(--amber); background: rgba(62,48,32,.35); }
.gate h3 { color: var(--amber); }
.phase-panel ul { margin: .7rem 0 0; padding-left: 1.1rem; color: var(--ink); font-size: .85rem; }
.phase-panel li + li { margin-top: .4rem; }
.compact-list { color: var(--muted) !important; }
.re-solve { display: flex; align-items: flex-start; gap: 1rem; margin-top: 2rem; padding-top: 1rem; border-top: 1px solid var(--line); color: var(--ink); font-size: .82rem; }
.re-solve > span { flex: 0 0 auto; color: var(--cyan); font: 600 .62rem/1.5 var(--mono); letter-spacing: .1em; }
.re-solve-list { margin: 0 !important; padding: 0 !important; list-style: none; }

.split-section { border-top: 1px solid var(--line); }
.practice-grid { display: grid; grid-template-columns: minmax(0, 1.3fr) minmax(260px, .7fr); gap: clamp(2rem, 8vw, 8rem); }
.rhythm-list { border-top: 1px solid var(--line); }
.rhythm-row { display: grid; grid-template-columns: 58px 1fr; gap: 1.2rem; padding: 1.15rem 0; border-bottom: 1px solid var(--line); }
.rhythm-count { color: var(--cyan); font: 400 1.55rem/1 var(--serif); }
.rhythm-row h3 { margin-bottom: .2rem; color: var(--ink); font: 700 .8rem/1.2 var(--mono); letter-spacing: .03em; text-transform: uppercase; }
.rhythm-row p { margin: 0; color: var(--muted); font-size: .88rem; }
.rule-card { position: relative; padding: 1.7rem; border: 1px solid var(--line-bright); background: var(--bg-raised); overflow: hidden; }
.rule-card h3 { margin-bottom: 1.3rem; font: 400 clamp(2rem, 3.8vw, 3.2rem)/.95 var(--serif); letter-spacing: -.06em; }
.rule-card p:not(.eyebrow) { max-width: 280px; color: var(--muted); font-size: .88rem; }
.rule-mark { position: absolute; right: 1rem; bottom: -.3rem; color: var(--cyan-deep); font: 400 8rem/1 var(--serif); }

.evidence-section { border-top: 1px solid var(--line); }
.evidence-grid { display: grid; grid-template-columns: minmax(0, 1.3fr) minmax(260px, .7fr); gap: clamp(2rem, 8vw, 8rem); }
.evidence-main { border-top: 1px solid var(--line); }
.evidence-line { display: grid; grid-template-columns: 54px 1fr; gap: 1.2rem; padding: 1.5rem 0; border-bottom: 1px solid var(--line); }
.evidence-index { color: var(--cyan); font: 400 1.3rem/1 var(--serif); }
.evidence-line h3 { margin-bottom: .45rem; font: 700 .76rem/1.2 var(--mono); letter-spacing: .05em; text-transform: uppercase; }
.evidence-line p { max-width: 570px; margin: 0; color: var(--muted); font-size: .9rem; }
.source-card { align-self: start; padding: 1.5rem; border: 1px solid var(--line); }
.source-note { color: var(--dim); font-size: .78rem; }
.source-card a { display: flex; justify-content: space-between; gap: 1rem; padding: .75rem 0; color: var(--ink); border-top: 1px solid var(--line); font: 600 .73rem/1.2 var(--mono); text-decoration: none; }
.source-card a:hover { color: var(--cyan); }
.source-card a span { color: var(--cyan); }
.site-footer { display: flex; justify-content: space-between; gap: 1rem; padding-top: 1.5rem; padding-bottom: 2rem; color: var(--dim); font: 600 .62rem/1.2 var(--mono); letter-spacing: .08em; text-transform: uppercase; }

.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }

@media (max-width: 720px) {
  .header-inner { min-height: 62px; }
  .header-note { display: none; }
  .hero { min-height: auto; padding-top: 4rem; padding-bottom: 4.5rem; grid-template-columns: 1fr; gap: 3rem; }
  h1 { font-size: clamp(3.55rem, 16vw, 5.5rem); }
  .current-card { max-width: 420px; }
  .current-card h2 { margin-top: 3rem; }
  .snapshot-strip { grid-template-columns: 1fr; gap: 1rem; padding-top: 1.5rem; padding-bottom: 1.5rem; }
  .snapshot-divider { width: 100%; height: 1px; }
  .snapshot-item, .snapshot-item:first-child { padding: .25rem 0; }
  .section-heading { grid-template-columns: 1fr; gap: 1.2rem; margin-bottom: 2rem; }
  .section-heading h2 { font-size: clamp(2.8rem, 13vw, 4.5rem); }
  .phase-toggle { grid-template-columns: 42px minmax(0, 1fr) 32px; gap: .65rem; }
  .phase-number { font-size: 1.25rem; }
  .phase-heading { display: block; }
  .phase-status { display: block; margin-bottom: .35rem; }
  .phase-title { font-size: 1.45rem; }
  .phase-panel { padding-inline: 42px; }
  .phase-columns, .practice-grid, .evidence-grid { grid-template-columns: 1fr; gap: 2rem; }
  .site-footer { display: block; }
  .site-footer span { display: block; }
  .site-footer span + span { margin-top: .7rem; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }
}