:root {
  /* brand primitives */
  --yellow: #F3FF97;
  --black:  #030206;
  --white:  #FFFFFC;
  --lilac:  #D5A5E3;
  --purple: #875CFF;
  --taupe:  #A89F91;

  /* surfaces — warm greige canvas (not light, not dark) */
  --bg:        #E3DFD7;
  --bg-warm:   #DCD7CD;
  --surface:   #FAF8F3;
  --surface-2: #FFFFFC;
  --line:      rgba(3, 2, 6, 0.10);
  --line-2:    rgba(3, 2, 6, 0.16);

  /* ink */
  --ink:       #1a1820;
  --ink-soft:  #4b4740;
  --ink-mute:  #726c61;

  /* purple tuned for legible links on light greige */
  --purple-ink: #6a3fe0;

  --radius:   14px;
  --radius-s: 9px;
  --maxw:     1180px;
  --shadow:   0 1px 0 rgba(3,2,6,0.04), 0 14px 36px -22px rgba(3,2,6,0.45);

  --sans: "IBM Plex Sans", system-ui, sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { animation: none !important; transition: none !important; }
}

body {
  margin: 0;
  font-family: var(--sans);
  font-weight: 400;
  color: var(--ink);
  background: var(--bg);
  background-image:
    radial-gradient(1100px 500px at 88% -8%, rgba(135,92,255,0.05), transparent 60%),
    radial-gradient(900px 460px at -5% 4%, rgba(213,165,227,0.07), transparent 55%);
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a { color: var(--purple-ink); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 3px; }
code {
  font-family: var(--mono);
  font-size: 0.86em;
  background: rgba(3,2,6,0.06);
  padding: 0.12em 0.4em;
  border-radius: 5px;
}

/* ---------- progress bar ---------- */
.progress-bar {
  position: fixed; top: 0; left: 0; height: 3px; width: 0;
  background: linear-gradient(90deg, var(--purple), var(--lilac));
  z-index: 120;
}

/* ---------- brand wordmark ---------- */
.brand { display: inline-flex; align-items: baseline; gap: 8px; color: var(--ink); }
.brand:hover { text-decoration: none; }
.brand__mark {
  font-weight: 700;
  font-size: 1.22rem;
  letter-spacing: -0.01em;
}
.brand__c { color: var(--purple); }
.brand__sub {
  font-family: var(--mono);
  font-size: 0.66rem;
  text-transform: uppercase;
  letter-spacing: 0.18em;
  color: var(--ink-mute);
  position: relative;
  top: -1px;
}

/* ---------- top nav ---------- */
.topnav {
  position: sticky; top: 0; z-index: 100;
  background: rgba(227, 223, 215, 0.82);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}
.topnav__inner {
  max-width: var(--maxw); margin: 0 auto;
  padding: 14px 26px;
  display: flex; align-items: center; gap: 24px;
}
.topnav__links { margin-left: auto; display: flex; gap: 26px; }
.topnav__links a {
  font-size: 0.9rem; color: var(--ink-soft); font-weight: 500;
}
.topnav__links a:hover { color: var(--ink); text-decoration: none; }

.toc-toggle {
  display: none; align-items: center; gap: 8px;
  margin-left: auto;
  background: var(--surface-2); border: 1px solid var(--line-2);
  border-radius: 8px; padding: 8px 13px;
  font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.04em;
  color: var(--ink); cursor: pointer;
}
.toc-toggle span {
  width: 15px; height: 2px; background: var(--ink); display: block;
}
.toc-toggle span:not(:first-child) { display: none; }

/* ---------- hero ---------- */
.hero {
  position: relative; overflow: hidden;
  background:
    radial-gradient(120% 130% at 78% -20%, rgba(135,92,255,0.55), transparent 55%),
    radial-gradient(90% 120% at 10% 120%, rgba(213,165,227,0.22), transparent 60%),
    var(--black);
  color: var(--white);
}
.hero__glow {
  position: absolute; inset: 0;
  background: radial-gradient(60% 60% at 85% 10%, rgba(243,255,151,0.10), transparent 60%);
  pointer-events: none;
}
.hero__inner {
  position: relative;
  max-width: var(--maxw); margin: 0 auto;
  padding: 84px 26px 70px;
}
.hero__title {
  font-size: clamp(2.6rem, 6vw, 4.4rem);
  line-height: 1.02;
  font-weight: 700;
  letter-spacing: -0.025em;
  margin: 14px 0 18px;
}
.hero__lede {
  max-width: 640px;
  font-size: clamp(1.02rem, 1.5vw, 1.2rem);
  color: rgba(255,255,252,0.78);
  font-weight: 300;
}

/* signature: the network progression rail */
.rail {
  position: relative;
  display: grid; grid-template-columns: repeat(3, 1fr);
  margin-top: 52px; max-width: 760px;
}
.rail__track {
  position: absolute; top: 7px; left: 6%; right: 6%; height: 2px;
  background: linear-gradient(90deg, rgba(243,255,151,0.25), var(--yellow), rgba(243,255,151,0.25));
}
.rail__stop { position: relative; display: flex; flex-direction: column; gap: 4px; padding-right: 14px; }
.rail__dot {
  width: 16px; height: 16px; border-radius: 50%;
  background: var(--yellow);
  box-shadow: 0 0 0 5px rgba(243,255,151,0.14);
  position: relative; z-index: 2;
}
.rail__name {
  margin-top: 12px;
  font-family: var(--mono); font-weight: 500;
  font-size: 1.05rem; letter-spacing: 0.01em;
}
.rail__role {
  font-size: 0.8rem; color: rgba(255,255,252,0.6);
}
.rail__note {
  margin-top: 26px;
  font-family: var(--mono); font-size: 0.78rem;
  color: rgba(255,255,252,0.55); letter-spacing: 0.01em;
}

/* ---------- layout ---------- */
.layout {
  max-width: var(--maxw); margin: 0 auto;
  padding: 0 26px;
  display: grid; grid-template-columns: 232px 1fr;
  gap: 56px; align-items: start;
}

/* ---------- side TOC ---------- */
.toc { position: sticky; top: 74px; align-self: start; }
.toc__inner {
  padding: 26px 0 40px;
  max-height: calc(100vh - 90px); overflow-y: auto;
  border-right: 1px solid var(--line);
  padding-right: 16px;
}
.toc__label {
  font-family: var(--mono);
  font-size: 0.66rem; text-transform: uppercase; letter-spacing: 0.16em;
  color: var(--ink-mute);
  margin: 22px 0 9px;
}
.toc__label:first-child { margin-top: 0; }
.toc__link {
  display: block;
  font-size: 0.86rem; color: var(--ink-soft);
  padding: 5px 0 5px 12px;
  border-left: 2px solid transparent;
  margin-left: -2px;
}
.toc__link:hover { color: var(--ink); text-decoration: none; }
.toc__link.is-active {
  color: var(--ink); font-weight: 600;
  border-left-color: var(--purple);
}

/* ---------- content ---------- */
.content { min-width: 0; padding-bottom: 90px; }

.eyebrow {
  font-family: var(--mono);
  font-size: 0.72rem; text-transform: uppercase; letter-spacing: 0.15em;
  color: var(--purple-ink); font-weight: 500;
  margin: 0 0 10px;
}
.eyebrow--light { color: var(--yellow); }

/* part markers */
.part-marker {
  margin: 64px 0 8px; padding: 40px 0 30px;
  border-top: 1px solid var(--line-2);
}
.part-marker:first-child { margin-top: 50px; }
.part-marker__no {
  font-family: var(--mono); font-size: 0.78rem; letter-spacing: 0.14em;
  text-transform: uppercase; color: var(--ink-mute);
}
.part-marker__title {
  font-size: clamp(1.9rem, 3.4vw, 2.7rem); font-weight: 700;
  letter-spacing: -0.02em; margin: 8px 0 10px;
}
.part-marker__desc { color: var(--ink-soft); max-width: 560px; margin: 0; }
.part-marker--dark {
  background:
    radial-gradient(100% 140% at 90% 0%, rgba(135,92,255,0.5), transparent 55%),
    var(--black);
  color: var(--white);
  border-radius: var(--radius);
  border: none;
  padding: 40px 36px;
  margin-top: 80px;
}
.part-marker--dark .part-marker__no { color: var(--yellow); }
.part-marker--dark .part-marker__desc { color: rgba(255,255,252,0.74); }

/* sections */
.section { padding: 40px 0; border-bottom: 1px solid var(--line); scroll-margin-top: 80px; }
.section__title {
  font-size: clamp(1.4rem, 2.6vw, 1.85rem); font-weight: 600;
  letter-spacing: -0.015em; margin: 0 0 14px;
}
.section__intro { color: var(--ink-soft); max-width: 660px; margin: 0 0 16px; }
.muted { color: var(--ink-mute); font-size: 0.92rem; }
.step__then { font-weight: 500; margin: 22px 0 10px; color: var(--ink); }

/* step head with mono number */
.step__head { display: flex; align-items: flex-start; gap: 20px; margin-bottom: 8px; }
.step__no {
  font-family: var(--mono); font-weight: 600;
  font-size: 1.35rem; color: var(--purple);
  background: var(--surface-2);
  border: 1px solid var(--line-2);
  border-radius: 11px;
  width: 52px; height: 52px; flex: none;
  display: grid; place-items: center;
  letter-spacing: -0.02em;
}
.step__head .section__title { margin: 2px 0 0; }

/* path picker */
.pathpicker { display: inline-flex; gap: 6px; padding: 5px; background: var(--surface-2); border: 1px solid var(--line-2); border-radius: 11px; margin-bottom: 26px; flex-wrap: wrap; }
.pathpicker__btn {
  font-family: var(--mono); font-size: 0.8rem; letter-spacing: 0.01em;
  border: none; background: transparent; color: var(--ink-soft);
  padding: 8px 16px; border-radius: 8px; cursor: pointer;
}
.pathpicker__btn:hover { color: var(--ink); }
.pathpicker__btn.is-active { background: var(--black); color: var(--white); }

/* dimmed steps when filtered */
.step.is-dimmed { opacity: 0.34; filter: grayscale(0.3); }
.step.is-dimmed .terminal { filter: grayscale(0.5); }

/* cards */
.cards-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin: 8px 0 4px; }
.pathcard, .optcard {
  background: var(--surface); border: 1px solid var(--line-2);
  border-radius: var(--radius); padding: 22px 22px;
}
.pathcard__title, .optcard__title { margin: 0 0 8px; font-size: 1.08rem; font-weight: 600; }
.pathcard p, .optcard p { margin: 0; color: var(--ink-soft); }
.pathcard__route {
  font-family: var(--mono); font-size: 0.9rem !important;
  color: var(--purple-ink) !important; margin-top: 12px !important;
}
.optcard--accent {
  background: var(--black); color: var(--white);
  border-color: var(--black);
  position: relative; overflow: hidden;
}
.optcard--accent::after {
  content:""; position: absolute; inset: 0;
  background: radial-gradient(80% 120% at 100% 0%, rgba(135,92,255,0.4), transparent 60%);
  pointer-events: none;
}
.optcard--accent .optcard__title { color: var(--yellow); position: relative; }
.optcard--accent p { color: rgba(255,255,252,0.78); position: relative; }
.inline-link { display: inline-block; margin-top: 12px; font-weight: 500; font-size: 0.9rem; }
.reqbox {
  background: var(--bg-warm); border: 1px solid var(--line-2);
  border-radius: var(--radius-s); padding: 16px 18px; margin: 18px 0;
}
.reqbox__label {
 font-weight: 800;  font-family: var(--black); font-size: 0.70rem; text-transform: uppercase;
  letter-spacing: 0.14em; color: var(--ink-black); margin: 0 0 6px;
}
.reqbox p:last-child { margin: 0; color: var(--ink-soft); }

/* terminal / code */
.terminal {
  background: var(--black); border-radius: var(--radius-s);
  overflow: hidden; margin: 16px 0;
  border: 1px solid #1c1a22;
}
.terminal__bar {
  display: flex; align-items: center; gap: 7px;
  padding: 10px 12px; background: #141219;
  border-bottom: 1px solid #221f2a;
}
.terminal__dot { width: 10px; height: 10px; border-radius: 50%; background: #3a3645; }
.terminal__dot:first-child { background: #5a5468; }
.terminal__title {
  font-family: var(--mono); font-size: 0.7rem; color: #8a8398;
  letter-spacing: 0.05em; margin-left: 6px;
}
.copy-btn {
  margin-left: auto;
  font-family: var(--mono); font-size: 0.68rem; letter-spacing: 0.04em;
  background: transparent; color: var(--yellow);
  border: 1px solid rgba(243,255,151,0.3); border-radius: 6px;
  padding: 4px 11px; cursor: pointer;
}
.copy-btn:hover { background: rgba(243,255,151,0.1); }
.copy-btn.is-copied { color: var(--lilac); border-color: rgba(213,165,227,0.4); }
.terminal__body {
  margin: 0; padding: 16px 18px; overflow-x: auto;
  font-family: var(--mono); font-size: 0.84rem; line-height: 1.7;
  color: #e9e6ef;
}
.terminal__body code { background: none; padding: 0; font-size: inherit; color: inherit; }

/* local UI grid */
.uigrid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; margin: 8px 0; }
.uigrid__item {
  background: var(--surface); border: 1px solid var(--line-2);
  border-radius: var(--radius-s); padding: 14px 16px;
  display: flex; flex-direction: column; gap: 4px;
}
.uigrid__role {
  font-family: var(--mono); font-size: 0.68rem; text-transform: uppercase;
  letter-spacing: 0.12em; color: var(--ink-mute);
}
.uigrid__item a { font-family: var(--mono); font-size: 0.82rem; }

/* substeps */
.substep { display: flex; gap: 18px; padding: 18px 0; border-top: 1px dashed var(--line-2); }
.substep:first-of-type { border-top: none; }
.substep__no {
  font-family: var(--mono); font-weight: 600; font-size: 0.95rem;
  color: var(--white); background: var(--purple);
  border-radius: 8px; width: 40px; height: 32px; flex: none;
  display: grid; place-items: center; margin-top: 2px;
}
.substep__body { min-width: 0; flex: 1; }
.substep__title { margin: 0 0 8px; font-size: 1.05rem; font-weight: 600; }
.substep__body p:first-of-type { margin-top: 0; color: var(--ink-soft); }

/* callouts */
.callout {
  display: flex; gap: 14px; align-items: flex-start;
  border-radius: var(--radius-s); padding: 15px 17px; margin: 18px 0;
  border: 1px solid var(--line-2); background: var(--surface);
}
.callout p { margin: 0; color: var(--ink-soft); }
.callout__tag {
  font-family: var(--mono); font-size: 0.66rem; text-transform: uppercase;
  letter-spacing: 0.1em; font-weight: 600;
  padding: 4px 9px; border-radius: 6px; white-space: nowrap; flex: none;
  background: var(--black); color: var(--yellow);
}
.callout__tag--purple { background: var(--purple); color: var(--white); }
.callout__tag--warn { background: var(--taupe); color: var(--black); }
.callout__tag--done { background: var(--yellow); color: var(--black); }
.callout--note { background: var(--bg-warm); }
.callout--warn { background: #f2ede4; border-color: rgba(168,159,145,0.5); }
.callout--soft { background: rgba(213,165,227,0.14); border-color: rgba(135,92,255,0.25); }
.callout--done {
  background: linear-gradient(90deg, rgba(243,255,151,0.28), rgba(243,255,151,0.08));
  border-color: rgba(3,2,6,0.18);
}

/* lists */
.bullets, .ordered { margin: 12px 0; padding-left: 0; color: var(--ink-soft); }
.bullets { list-style: none; }
.bullets li { position: relative; padding-left: 22px; margin: 8px 0; }
.bullets li::before {
  content: ""; position: absolute; left: 2px; top: 10px;
  width: 6px; height: 6px; border-radius: 50%; background: var(--purple);
}
.ordered { padding-left: 20px; }
.ordered li { margin: 8px 0; padding-left: 4px; }
.ordered li::marker { font-family: var(--mono); color: var(--purple-ink); font-weight: 600; }

.linklist { list-style: none; padding: 0; margin: 14px 0 0; }
.linklist li { margin: 6px 0; }
.linklist a {
  font-weight: 600; font-size: 1rem;
  display: inline-flex; align-items: center; gap: 7.5px;
}
.linklist a::before { content: "↗"; font-size: 0.8em; color: var(--ink-mute); }

/* subhead inside steps */
.subhead {
  font-size: 1.04rem; font-weight: 600; margin: 26px 0 10px;
  padding-top: 4px;
}

/* quality list */
.quality-list { display: grid; gap: 12px; margin-top: 8px; }
.quality {
  background: var(--surface); border: 1px solid var(--line);
  border-left: 3px solid var(--purple);
  border-radius: var(--radius-s); padding: 14px 18px;
}
.quality__name { font-weight: 600; margin: 0 0 4px; }
.quality p:last-child { margin: 0; color: var(--ink-soft); font-size: 0.94rem; }

/* tags */
.tag-grid { display: flex; flex-wrap: wrap; gap: 9px; margin-top: 6px; }
.tag {
  font-size: 0.88rem; font-weight: 500;
  background: var(--surface-2); border: 1px solid var(--line-2);
  border-radius: 100px; padding: 8px 16px; color: var(--ink-soft);
}

/* resources */
.resources { border-bottom: none; }
.res-group { margin-top: 24px; }
.res-group__label {
  font-family: var(--mono); font-size: 0.7rem; text-transform: uppercase;
  letter-spacing: 0.14em; color: var(--ink-mute); margin: 0 0 12px;
}
.res-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 10px; }
.res {
  display: flex; flex-direction: column; gap: 3px;
  background: var(--surface); border: 1px solid var(--line-2);
  border-radius: var(--radius-s); padding: 13px 16px;
  transition: border-color 0.16s ease, transform 0.16s ease;
}
.res:hover { text-decoration: none; border-color: var(--purple); transform: translateY(-1px); }
.res__name { font-weight: 600; color: var(--ink); font-size: 0.94rem; }
.res__url { font-family: var(--mono); font-size: 0.74rem; color: var(--ink-mute); }

/* footer */
.footer {
  background: var(--black); color: var(--white);
  margin-top: 30px;
}
.footer__inner {
  max-width: var(--maxw); margin: 0 auto; padding: 40px 26px;
  display: flex; align-items: center; gap: 18px; flex-wrap: wrap;
}
.brand--footer { color: var(--white); }
.brand--footer .brand__c { color: var(--yellow); }
.brand--footer .brand__sub { color: rgba(255,255,252,0.5); }
.footer__note { color: rgba(255,255,252,0.6); font-size: 0.88rem; margin: 0; }
.footer__site {
  margin-left: auto; font-family: var(--mono); font-size: 0.82rem;
  color: var(--yellow);
}

/* toast */
.toast {
  position: fixed; bottom: 26px; left: 50%; transform: translateX(-50%) translateY(20px);
  background: var(--black); color: var(--white);
  font-family: var(--mono); font-size: 0.8rem; letter-spacing: 0.02em;
  padding: 11px 20px; border-radius: 9px;
  opacity: 0; pointer-events: none; transition: opacity 0.2s ease, transform 0.2s ease;
  z-index: 130; border: 1px solid #2a2733;
}
.toast.is-shown { opacity: 1; transform: translateX(-50%) translateY(0); }

/* ---------- responsive ---------- */
@media (max-width: 900px) {
  .layout { grid-template-columns: 1fr; gap: 0; }
  .toc {
    position: fixed; top: 58px; left: 0; right: 0; z-index: 90;
    background: var(--bg); border-bottom: 1px solid var(--line-2);
    max-height: 0; overflow: hidden; transition: max-height 0.25s ease;
  }
  .toc.is-open { max-height: 70vh; overflow-y: auto; box-shadow: var(--shadow); }
  .toc__inner { border-right: none; padding: 16px 26px 24px; max-height: none; }
  .toc-toggle { display: inline-flex; }
  .topnav__links { display: none; }
  .topnav__inner { gap: 14px; }
}

@media (max-width: 620px) {
  .topnav__inner { padding: 12px 18px; }
  .hero__inner { padding: 60px 18px 52px; }
  .layout { padding: 0 18px; }
  .rail { grid-template-columns: 1fr; gap: 22px; }
  .rail__track { display: none; }
  .rail__stop { flex-direction: row; align-items: center; gap: 12px; padding: 0; }
  .rail__name { margin-top: 0; }
  .rail__dot { margin-top: 0; }
  .cards-2, .uigrid, .res-grid { grid-template-columns: 1fr; }
  .step__head { gap: 14px; }
  .step__no { width: 44px; height: 44px; font-size: 1.1rem; }
  .substep { flex-direction: column; gap: 10px; }
  .part-marker--dark { padding: 30px 22px; }
  .footer__site { margin-left: 0; }
}