/* ============================================================================
   chemist — "Routing trace" identity (A), with an annotated session (from D)
   and a documented size-cliff figure + abort schematic (from C), all unified
   under one system.
   ----------------------------------------------------------------------------
   PALETTE = CPK atom-coloring. Each color carries meaning, on purpose:
     --ink   #15171c  carbon (graphite)   -> body + headline text
     --blue  #2740c9  nitrogen            -> the SELECTED route, links, primary actions
     --red   #b23529  oxygen              -> REFUSALS + honest ceilings (used sparingly)
     --paper #eceef1  cool engineering-paper background (NOT cream)
     --panel #f7f8fa  hydrogen (white)    -> raised panels
     --rule  #d2d6dc  hairline rules
   Boldness is spent on the trace, the session, and the figures; the rest is flat.
   ========================================================================== */

:root {
  --ink:        #15171c;   /* carbon  */
  --ink-soft:   #494f59;
  --blue:       #2740c9;   /* nitrogen */
  --blue-deep:  #1d2f97;
  --red:        #b23529;   /* oxygen   */
  --paper:      #eceef1;   /* cool paper */
  --panel:      #f7f8fa;   /* hydrogen white */
  --panel-2:    #fbfcfd;
  --rule:       #d2d6dc;   /* hairline */
  --rule-soft:  #e2e5ea;

  /* terminal syntax (on graphite bg) — same meanings, lightened for contrast */
  --t-bg:       #15171c;
  --t-fg:       #e7eaf2;
  --t-mut:      #8b93a6;
  --t-route:    #8b9dff;   /* nitrogen, lightened: selected route names */
  --t-rej:      #ef8a80;   /* oxygen, lightened: REJECT / ABORT */
  --t-ok:       #7cc7a0;   /* sparingly: an ok/summary line */
  --t-str:      #b3bce0;

  --mono: "Space Mono", ui-monospace, "SFMono-Regular", Menlo, monospace;
  --sans: "IBM Plex Sans", system-ui, -apple-system, Segoe UI, Roboto, sans-serif;

  --maxw: 1140px;
  --pad:  clamp(1rem, 4vw, 2.5rem);
}

/* ---------- reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }
img, svg { max-width: 100%; }

/* skip link */
.skip {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--ink);
  color: #fff;
  padding: 0.6rem 1rem;
  font-family: var(--mono);
  font-size: 0.8rem;
  z-index: 100;
}
.skip:focus { left: 0.5rem; top: 0.5rem; }

/* ---------- shared layout ---------- */
.wrap { width: 100%; max-width: var(--maxw); margin: 0 auto; padding-inline: var(--pad); }

.eyebrow {
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.02em;
  color: var(--ink-soft);
  text-transform: none;
  margin: 0;
}
.brand-mark { font-family: var(--mono); font-weight: 700; letter-spacing: -0.01em; color: var(--ink); }

/* ---------- links ---------- */
a { color: var(--blue); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 2px; }
:focus-visible { outline: 2px solid var(--blue); outline-offset: 2px; }

/* ============================================================================
   HEADER — slim sticky
   ========================================================================== */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(236, 238, 241, 0.92);
  backdrop-filter: saturate(140%) blur(6px);
  border-bottom: 1px solid var(--rule);
}
.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  min-height: 54px; gap: 1rem;
}
.brand { font-size: 1rem; }
.brand:hover { text-decoration: none; }
.site-nav {
  display: flex; gap: clamp(0.6rem, 2.2vw, 1.6rem);
  font-family: var(--mono); font-size: 0.82rem; flex-wrap: wrap; justify-content: flex-end;
}
.site-nav a { color: var(--ink); }
.site-nav a:hover { color: var(--blue); }

/* ============================================================================
   HERO
   ========================================================================== */
.hero {
  position: relative;
  border-bottom: 1px solid var(--rule);
  background-image:
    linear-gradient(to right, rgba(39, 64, 201, 0.045) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(39, 64, 201, 0.045) 1px, transparent 1px);
  background-size: 28px 28px;
  background-position: center top;
}
.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr);
  gap: clamp(1.5rem, 4vw, 3.25rem);
  padding-block: clamp(2.5rem, 6vw, 4.5rem);
  align-items: start;
}
.hero-copy .eyebrow { margin-bottom: 1rem; }
.hero-headline {
  font-family: var(--mono); font-weight: 700;
  font-size: clamp(1.6rem, 5.4vw, 3.4rem);
  line-height: 1.02; letter-spacing: -0.035em;
  margin: 0 0 1.25rem; color: var(--ink);
  overflow-wrap: break-word; word-break: break-word;
}
.lede {
  font-family: var(--sans);
  font-size: clamp(1rem, 1.4vw, 1.12rem);
  line-height: 1.62; color: var(--ink-soft);
  max-width: 46ch; margin: 0 0 1.75rem;
}
.lede em { font-style: italic; color: var(--ink); }
.actions { display: flex; flex-wrap: wrap; gap: 0.75rem; margin-bottom: 1.5rem; }
.btn {
  font-family: var(--mono); font-size: 0.85rem; font-weight: 700; letter-spacing: -0.01em;
  padding: 0.6rem 1.1rem; border: 1px solid var(--blue); border-radius: 2px; display: inline-block;
}
.btn:hover { text-decoration: none; }
.btn-primary { background: var(--blue); color: #fff; border-color: var(--blue); }
.btn-primary:hover { background: var(--blue-deep); border-color: var(--blue-deep); }
.btn-secondary { background: transparent; color: var(--blue); }
.btn-secondary:hover { background: rgba(39, 64, 201, 0.07); }
.hero-foot { margin-top: 0.25rem; }

/* ============================================================================
   TRACE — signature 1 (interactive)
   ========================================================================== */
.trace {
  background: var(--panel); border: 1px solid var(--ink); border-radius: 2px;
  font-family: var(--mono); box-shadow: 4px 4px 0 0 var(--rule);
}
.trace-head {
  display: flex; align-items: baseline; justify-content: space-between; gap: 0.75rem;
  padding: 0.8rem 1rem; border-bottom: 1px solid var(--rule); background: var(--panel-2); flex-wrap: wrap;
}
.trace-title { font-weight: 700; font-size: 0.82rem; letter-spacing: 0.01em; color: var(--ink); }
.trace-sub { font-size: 0.7rem; }
.seg { display: flex; flex-wrap: wrap; gap: 1px; padding: 0.6rem 0.7rem 0; background: var(--panel); }
.seg-btn {
  font-family: var(--mono); font-size: 0.76rem; font-weight: 700; letter-spacing: -0.01em;
  color: var(--ink-soft); background: var(--paper);
  border: 1px solid var(--rule); border-bottom: none; border-radius: 2px 2px 0 0;
  padding: 0.45rem 0.7rem; cursor: pointer; position: relative; top: 1px;
}
.seg-btn:hover { color: var(--ink); }
.seg-btn[aria-selected="true"] {
  color: var(--blue); background: var(--panel); border-color: var(--ink); border-bottom: 1px solid var(--panel);
}
.trace-panel { padding: 1.1rem 1.1rem 1.25rem; border-top: 1px solid var(--ink); }
.trace-panel[hidden] { display: none; }
.req { font-size: 0.82rem; font-weight: 700; color: var(--ink); margin: 0 0 0.9rem; line-height: 1.45; word-break: break-word; }
.tree { list-style: none; margin: 0 0 0.85rem; padding: 0; }
.tree li {
  display: grid; grid-template-columns: 1.4em auto 1fr; align-items: baseline;
  gap: 0.4rem 0.55rem; font-size: 0.8rem; padding: 0.18rem 0; line-height: 1.45;
}
.branch { color: var(--ink-soft); font-weight: 700; }
.be { font-weight: 700; }
.reason { grid-column: 3; color: var(--ink-soft); font-size: 0.78rem; }
.tag {
  font-size: 0.62rem; font-weight: 700; letter-spacing: 0.04em;
  padding: 0.08rem 0.4rem; border-radius: 2px; border: 1px solid currentColor;
  white-space: nowrap; align-self: center;
}
.tag-rej  { color: var(--red); }
.tag-sel  { color: var(--blue); }
.tag-ceil { color: var(--ink-soft); }
.rej .be, .rej .reason { color: var(--red); text-decoration: line-through; text-decoration-thickness: 1px; }
.sel .be { color: var(--blue); }
.sel { background: rgba(39, 64, 201, 0.05); border-radius: 2px; }
.contract {
  margin: 0; padding-top: 0.7rem; border-top: 1px dashed var(--rule);
  font-size: 0.76rem; color: var(--ink); line-height: 1.5;
  display: flex; gap: 0.5rem; align-items: baseline; flex-wrap: wrap;
}
@media (prefers-reduced-motion: no-preference) {
  .trace-panel.reveal { animation: traceReveal 0.28s ease both; }
  @keyframes traceReveal { from { opacity: 0; transform: translateY(4px); } to { opacity: 1; transform: none; } }
}

/* ============================================================================
   BANDS — quiet flat sections
   ========================================================================== */
.band { border-bottom: 1px solid var(--rule); }
.band > .wrap { padding-block: clamp(2.5rem, 6vw, 4rem); }
.section-h {
  font-family: var(--mono); font-weight: 700;
  font-size: clamp(1.3rem, 3vw, 2rem); letter-spacing: -0.03em; line-height: 1.1;
  margin: 0 0 0.6rem; color: var(--ink);
  overflow-wrap: break-word;
}
.section-lede {
  font-family: var(--sans); color: var(--ink-soft); max-width: 64ch; margin: 0 0 1.9rem; font-size: 1rem;
}
.section-lede em { font-style: italic; color: var(--ink); }
.section-lede code { font-family: var(--mono); font-size: 0.85em; color: var(--ink); }
.section-lede .data { font-family: var(--mono); font-weight: 700; color: var(--blue); }

/* ============================================================================
   SESSION — signature 2 (annotated claude -p transcript)
   ========================================================================== */
.session { display: grid; grid-template-columns: minmax(0, 1.45fr) minmax(0, 1fr); gap: 1.25rem; align-items: start; }
.session-term {
  background: var(--t-bg); border: 1px solid var(--ink); border-radius: 2px; overflow: hidden;
  box-shadow: 4px 4px 0 0 var(--rule);
}
.term-bar {
  display: flex; align-items: center; gap: 0.5rem;
  padding: 0.5rem 0.85rem; border-bottom: 1px solid #2a2d36; background: #1b1e25;
}
.term-name { font-family: var(--mono); font-size: 0.72rem; color: var(--t-mut); }
.log { list-style: none; margin: 0; padding: 0.85rem 0.6rem 1rem; font-family: var(--mono); font-size: 0.78rem; }
.logline { display: grid; grid-template-columns: 1.7em 1fr; gap: 0.5rem; padding: 0.22rem 0; line-height: 1.5; }
.ln { color: #4b5060; text-align: right; user-select: none; }
.lc { color: var(--t-fg); white-space: pre-wrap; word-break: break-word; }
.sh { color: var(--t-route); font-weight: 700; }
.pr { color: var(--t-mut); }
.str { color: var(--t-str); }
.mut { color: var(--t-mut); }
.rt  { color: var(--t-route); font-weight: 700; }
.ok  { color: var(--t-ok); }
.rej-t { color: var(--t-rej); font-weight: 700; }
.sel-t { color: var(--t-route); font-weight: 700; }

.session-notes { display: flex; flex-direction: column; gap: 0.9rem; }
.snote {
  font-family: var(--sans); font-style: italic; font-size: 0.9rem; line-height: 1.55;
  color: var(--ink-soft); margin: 0; padding-left: 0.9rem; border-left: 2px solid var(--rule);
}
.snote em { font-style: normal; font-weight: 600; color: var(--ink); }
.snote-k {
  display: block; font-family: var(--mono); font-style: normal; font-weight: 700;
  font-size: 0.66rem; letter-spacing: 0.03em; color: var(--ink-soft); margin-bottom: 0.25rem;
}
.snote-rej { border-left-color: var(--red); }
.snote-rej .snote-k { color: var(--red); }
.snote-sel { border-left-color: var(--blue); }
.snote-sel .snote-k { color: var(--blue); }

/* ============================================================================
   FIGURES — captions + shared SVG type
   ========================================================================== */
.axis-cap {
  font-family: var(--mono); font-size: 0.78rem; color: var(--ink-soft);
  line-height: 1.5; margin: 0 0 0.9rem; max-width: 80ch;
}
.fig-label { font-weight: 700; color: var(--blue); margin-right: 0.5rem; letter-spacing: 0.02em; }

/* ---- FIG 1: size-cliff axis ---- */
.axis-fig { margin: 0 0 2rem; }
.axis-scroll {
  background: var(--panel); border: 1px solid var(--rule); border-radius: 2px;
  padding: 0.75rem 0.5rem; overflow-x: auto;
}
.axis-svg { display: block; width: 100%; min-width: 540px; height: auto; }
.axis-svg text { font-family: var(--mono); }
.axis-svg .grid line { stroke: var(--rule); stroke-width: 1; }
.cliff-line { stroke: var(--red); stroke-width: 1.4; stroke-dasharray: 3 3; }
.hatch-line { stroke: var(--red); stroke-width: 1.1; opacity: 0.16; }
.band-r { fill: rgba(73, 79, 89, 0.14); stroke: var(--ink-soft); stroke-width: 1; }
.band-r.sel-band { fill: rgba(39, 64, 201, 0.16); stroke: var(--blue); }
.band-r.tail { fill: none; stroke: var(--blue); stroke-dasharray: 4 4; }
.band-label { font-size: 12px; fill: var(--ink); }
.marker-line { stroke: var(--blue); stroke-width: 1.6; }
.marker-cap { fill: var(--blue); }
.marker-note { font-size: 11px; font-weight: 700; fill: var(--blue); }
.cliff-note { font-size: 11px; fill: var(--red); }
.ceil-note-svg { font-size: 10.5px; fill: var(--ink-soft); }
.axis-x { stroke: var(--ink); stroke-width: 1.2; }
.ticks text { font-size: 11px; fill: var(--ink-soft); text-anchor: middle; }
.axis-title { font-size: 11px; fill: var(--ink-soft); }

/* ---- BACKENDS spec table ---- */
.spec {
  width: 100%; border-collapse: collapse; font-family: var(--mono); font-size: 0.82rem;
  border: 1px solid var(--rule); background: var(--panel);
}
.spec thead th {
  text-align: left; font-weight: 700; font-size: 0.7rem; letter-spacing: 0.05em; color: var(--ink-soft);
  background: var(--panel-2); padding: 0.7rem 0.85rem; border-bottom: 1px solid var(--ink); vertical-align: bottom;
}
.spec tbody th, .spec tbody td {
  padding: 0.7rem 0.85rem; border-bottom: 1px solid var(--rule-soft); vertical-align: top; text-align: left; line-height: 1.45;
}
.spec tbody tr:last-child th, .spec tbody tr:last-child td { border-bottom: none; }
.spec tbody th { font-weight: 700; color: var(--ink); white-space: nowrap; }
.spec td { color: var(--ink-soft); }
.via { font-weight: 400; color: var(--ink-soft); font-size: 0.9em; }
.spec td.ceil, .ceil { color: var(--red); }
.ceil-key { font-family: var(--mono); color: var(--red); font-weight: 700; }

/* ============================================================================
   GUARDRAIL — contract + FIG 2 schematic
   ========================================================================== */
.guard-grid { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: clamp(1.5rem, 4vw, 3rem); align-items: center; }
.guard-body { font-family: var(--sans); color: var(--ink-soft); max-width: 52ch; margin: 0 0 1.25rem; }
.guard-body strong { color: var(--ink); }
.guard-facts { list-style: none; margin: 0; padding: 0; font-family: var(--mono); font-size: 0.8rem; border-top: 1px solid var(--rule); }
.guard-facts li { padding: 0.55rem 0; border-bottom: 1px solid var(--rule-soft); color: var(--ink); }
.gf-k { display: inline-block; min-width: 9ch; color: var(--ink-soft); font-size: 0.7rem; letter-spacing: 0.04em; margin-right: 0.6rem; }
.guard-fig { margin: 0; }
.guard-svg {
  display: block; width: 100%; height: auto; background: var(--panel);
  border: 1px solid var(--rule); border-radius: 2px; padding: 0.5rem;
}
.guard-svg text { font-family: var(--mono); }
.g-grid line { stroke: var(--rule-soft); stroke-width: 1; }
.g-axis { stroke: var(--ink); stroke-width: 1.2; }
.g-threshold { stroke: var(--red); stroke-width: 1.4; stroke-dasharray: 4 3; }
.g-thlabel { font-size: 10px; fill: var(--red); }
.g-trace { fill: none; stroke-width: 2; }
.g-trace.ok { stroke: var(--ink-soft); }
.g-trace.bad { stroke: var(--red); }
.g-abort { fill: var(--red); }
.g-abortlabel { font-size: 10px; fill: var(--red); }
.g-tick { font-size: 10px; fill: var(--ink-soft); }
.g-ylab, .g-xlab { font-size: 10px; fill: var(--ink-soft); }

/* ============================================================================
   SKILL plates
   ========================================================================== */
.plates { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1.25rem; }
.plate { background: var(--panel); border: 1px solid var(--rule); border-radius: 2px; padding: 1.4rem 1.4rem 1.5rem; }
.plate-head {
  display: flex; align-items: baseline; justify-content: space-between; gap: 0.75rem; flex-wrap: wrap;
  padding-bottom: 0.75rem; margin-bottom: 0.95rem; border-bottom: 1px solid var(--rule);
}
.plate-name { font-family: var(--mono); font-weight: 700; font-size: 1.1rem; letter-spacing: -0.02em; color: var(--ink); }
.plate-kind { font-size: 0.7rem; }
.plate-body { font-family: var(--sans); font-size: 0.94rem; color: var(--ink-soft); margin: 0 0 1rem; line-height: 1.55; }
.plate-list { list-style: none; margin: 0 0 1.15rem; padding: 0; font-family: var(--mono); font-size: 0.78rem; color: var(--ink); }
.plate-list li { padding: 0.18rem 0; line-height: 1.4; }
.plate-list .branch { color: var(--ink-soft); margin-right: 0.35rem; }
.plate-link { font-family: var(--mono); font-weight: 700; font-size: 0.82rem; color: var(--blue); }
.planned { margin-top: 1.5rem; font-size: 0.78rem; }
.planned strong { color: var(--ink); font-weight: 700; }

/* ============================================================================
   INSTALL
   ========================================================================== */
.code-cols { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1.25rem; }
.code-cap { margin-bottom: 0.55rem; font-weight: 700; }
.code {
  margin: 0; background: var(--ink); color: #e7eaf2; border: 1px solid var(--ink); border-radius: 2px;
  padding: 1rem 1.05rem; overflow-x: auto; font-family: var(--mono); font-size: 0.76rem; line-height: 1.7;
}
.code code { font-family: var(--mono); white-space: pre; }

/* ============================================================================
   FOOTER
   ========================================================================== */
.site-footer { background: var(--panel); border-top: 1px solid var(--rule); }
.footer-inner { display: flex; align-items: center; justify-content: space-between; gap: 1rem; flex-wrap: wrap; padding-block: 1.5rem; }
.footer-meta { font-size: 0.76rem; }
.footer-meta a { color: var(--blue); }

/* ============================================================================
   RESPONSIVE
   ========================================================================== */
@media (max-width: 880px) {
  .hero-grid { grid-template-columns: 1fr; }
  .session { grid-template-columns: 1fr; }
  .guard-grid { grid-template-columns: 1fr; }
  .plates { grid-template-columns: 1fr; }
  .code-cols { grid-template-columns: 1fr; }
}
@media (max-width: 560px) {
  .header-inner { flex-wrap: wrap; min-height: 0; padding-block: 0.55rem; gap: 0.45rem 0.75rem; }
  .site-nav { width: 100%; justify-content: flex-start; }
}
@media (max-width: 640px) {
  .spec, .spec thead, .spec tbody, .spec tr, .spec th, .spec td { display: block; width: 100%; }
  .spec thead { display: none; }
  .spec tbody tr { border-bottom: 1px solid var(--ink); padding: 0.6rem 0; }
  .spec tbody tr:last-child { border-bottom: none; }
  .spec tbody th, .spec tbody td { border-bottom: none; padding: 0.25rem 0.85rem; white-space: normal; }
  .spec tbody td::before {
    content: attr(data-label) ":  "; color: var(--ink-soft); font-size: 0.66rem;
    letter-spacing: 0.04em; display: inline; margin-right: 0.3rem;
  }
  .spec tbody th { font-size: 0.95rem; padding-top: 0.5rem; }
}
@media (max-width: 420px) {
  .site-nav { gap: 0.6rem; font-size: 0.72rem; }
  .seg-btn { flex: 1 1 auto; text-align: center; }
  .trace, .session-term { box-shadow: 3px 3px 0 0 var(--rule); }
  .tree li { grid-template-columns: 1.2em auto 1fr; }
}