/* Self-Evolving Network Verifiers project page, in the style of common academic
   project pages: centred title block, sans-serif type, pill buttons.
   Dark by default; html[data-theme="light"] switches to the light palette. */

:root {
  --paper: #0f1216;
  --panel: #171b21;
  --ink: #e6e9ee;
  --muted: #9aa4b2;
  --rule: #2a313b;
  --rule-strong: #3d4652;
  --signal: #f47067;
  --ok: #57ab5a;
  --accent: #539bf5;
  --on-accent: #ffffff;
  --area-1: #39c5bb;
  --area-2: #e0b04a;
  --area-3: #c48df0;
  --signal-wash: #3a1e1e;
  --ok-wash: #19301f;
  --grid: rgba(255, 255, 255, 0.05);
  --route-model: #ff7ac8;
  --route-oracle: #ffd54a;
  --route-oracle-ink: #ffd54a;
  --decider-wash: #3a3214;
  --pill: #2a3039;
  --pill-ink: #f0f3f6;
  --glow-1: rgba(83, 155, 245, 0.16);
  --glow-2: rgba(196, 141, 240, 0.10);

  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Noto Sans", "Helvetica Neue", Arial, sans-serif;
  --mono: ui-monospace, "SFMono-Regular", "SF Mono", Menlo, Consolas, "Liberation Mono", "DejaVu Sans Mono", monospace;

  --radius: 10px;
  --gutter: 16px;
  color-scheme: dark;
}

:root[data-theme="light"] {
  --paper: #ffffff;
  --panel: #f6f8fa;
  --ink: #1f2328;
  --muted: #59636e;
  --rule: #d8dee4;
  --rule-strong: #afb8c1;
  --signal: #cf222e;
  --ok: #1a7f37;
  --accent: #0969da;
  --area-1: #0d766f;
  --area-2: #8f6200;
  --area-3: #7a3f8c;
  --signal-wash: #ffebe9;
  --ok-wash: #dafbe1;
  --grid: rgba(31, 35, 40, 0.07);
  --route-model: #bf3989;
  --route-oracle: #e3a600;
  --route-oracle-ink: #9a6700;
  --decider-wash: #fff8c5;
  --pill: #363636;
  --pill-ink: #ffffff;
  --glow-1: rgba(9, 105, 218, 0.10);
  --glow-2: rgba(122, 63, 140, 0.07);
  color-scheme: light;
}

*, *::before, *::after { box-sizing: border-box; }

html { font-size: 16px; -webkit-text-size-adjust: 100%; }
html.kiosk { font-size: 22px; }

body {
  margin: 0;
  background:
    radial-gradient(60rem 32rem at 15% -8rem, var(--glow-1), transparent 70%),
    radial-gradient(50rem 30rem at 90% -4rem, var(--glow-2), transparent 70%),
    var(--paper);
  background-repeat: no-repeat;
  color: var(--ink);
  font-family: var(--sans);
  line-height: 1.5;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
}

main { flex: 1 0 auto; outline: none; }

/* the drifting network behind the page (js/backdrop.js); dimmer under the text column */
.backdrop {
  position: fixed; inset: 0; width: 100%; height: 100%;
  z-index: -1; pointer-events: none;
  -webkit-mask-image: radial-gradient(ellipse 42% 60% at 50% 45%, rgba(0, 0, 0, 0.3), #000 100%);
  mask-image: radial-gradient(ellipse 42% 60% at 50% 45%, rgba(0, 0, 0, 0.3), #000 100%);
}

a { color: var(--accent); }

:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 2px;
  border-radius: 3px;
}

.skip {
  position: absolute; left: -999px; top: 8px;
  background: var(--ink); color: var(--paper); padding: 6px 10px; z-index: 10;
}
.skip:focus { left: 8px; }

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

.wrap {
  width: 100%;
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 var(--gutter);
}

/* ---------- type ---------- */

.display, .display-sm, .card-title, .level-card h2 {
  font-family: var(--sans);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.15;
  margin: 0;
}
.display { font-size: clamp(2.2rem, 6vw, 3.2rem); }
.display-sm { font-size: clamp(1.6rem, 4vw, 2.2rem); }

.kicker, .label {
  font-family: var(--sans);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--muted);
  margin: 0 0 0.5rem;
}
.kicker-signal { color: var(--signal); }

/* glyphs some system text fonts lack (e.g. U+2260 on Noto Sans) */
.sym {
  font-family: -apple-system, "Segoe UI", "DejaVu Sans", "Segoe UI Symbol", "Apple Symbols", "Cambria Math", "STIX Two Math", "DejaVu Sans Mono", var(--mono);
  font-style: normal;
}

code {
  font-family: var(--mono);
  font-size: 0.9em;
  background: var(--paper);
  border: 1px solid var(--rule);
  border-radius: 3px;
  padding: 0 0.25em;
  overflow-wrap: anywhere;
}

/* ---------- page top (story and explorer) ---------- */

.crumbs {
  display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between;
  gap: 0.5rem 1rem; margin: 0 0 1.25rem;
}

/* ---------- buttons ---------- */

button { font: inherit; color: inherit; }

.btn-primary, .btn-secondary, .btn-quiet, .pill {
  cursor: pointer;
  border-radius: 999px;
  font-weight: 600;
  line-height: 1.2;
  padding: 0.65rem 1.2rem;
  border: 1px solid transparent;
  min-height: 2.6rem;
  text-decoration: none;
  display: inline-flex; align-items: center; justify-content: center; gap: 0.45rem;
}
.btn-primary { background: var(--accent); color: var(--on-accent); }
.btn-primary:hover { filter: brightness(1.1); }
.btn-secondary { background: transparent; border-color: var(--rule-strong); color: var(--ink); }
.btn-secondary:hover { background: var(--panel); }
.btn-quiet {
  background: transparent; border-color: var(--rule); color: var(--muted);
  padding: 0.35rem 0.85rem; min-height: 2.1rem; font-size: 0.88rem;
}
.btn-quiet:hover { color: var(--ink); border-color: var(--rule-strong); }
.pill { background: var(--pill); color: var(--pill-ink); border-color: var(--rule); }
.pill:hover { filter: brightness(1.15); }
.pill .icon { width: 18px; height: 18px; color: inherit; }
.linklike {
  all: unset; cursor: pointer; color: var(--accent);
  text-decoration: underline; text-underline-offset: 3px; font-weight: 600;
}
.linklike:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }

.actions { display: flex; flex-wrap: wrap; gap: 0.75rem; margin-top: 1.5rem; }

/* ---------- landing ---------- */

.screen { padding-top: clamp(1.5rem, 4vw, 3rem); padding-bottom: 3rem; }

.landing { max-width: 900px; }
.proj-hero { text-align: center; padding: clamp(1rem, 4vw, 2.5rem) 0 0.5rem; }
/* The title stays on one line, shrinking with the viewport; on phones, where one line
   would make it smaller than the author names, it wraps instead. */
.proj-hero .display { margin: 0 auto; white-space: nowrap; font-size: clamp(1.75rem, 5vw, 3.2rem); }
@media (max-width: 560px) { .proj-hero .display { white-space: normal; font-size: 2rem; } }
.authors { margin: 1.1rem 0 0.2rem; font-size: 1.2rem; color: var(--ink); }
.affil, .venue { margin: 0.15rem 0; font-size: 1.05rem; color: var(--muted); }
.venue { font-weight: 600; color: var(--ink); }
.hero-links { display: flex; flex-wrap: wrap; justify-content: center; gap: 0.6rem; margin: 1.3rem 0 0; }
.proj-h:focus { outline: none; }
.proj-sec { margin-top: 3rem; }
.proj-h {
  font-family: var(--sans); font-size: 1.75rem; font-weight: 700; letter-spacing: -0.01em;
  text-align: center; color: var(--ink); margin: 0 0 1rem;
}
.proj-sec .lead { margin-left: auto; margin-right: auto; margin-bottom: 1.1rem; }
.proj-sec .contrast { justify-content: center; }
/* icons and the system diagram */
.icon { fill: none; stroke: currentColor; stroke-width: 1.6; stroke-linecap: round; stroke-linejoin: round; overflow: visible; }
.icon .fill { fill: currentColor; stroke: none; }
.icon .bg { fill: var(--panel); }
.icon .dash { stroke-dasharray: 2 2.5; }
.icon-html { flex: none; color: var(--accent); }
.contrast { display: flex; flex-wrap: wrap; align-items: center; gap: 0.75rem 1rem; margin: 0.2rem 0 0; }
.contrast-item {
  display: flex; align-items: center; gap: 0.6rem; padding: 0.6rem 0.85rem; max-width: 22rem;
  background: var(--panel); border: 1px solid var(--rule); border-radius: var(--radius); font-size: 0.95rem;
}
.contrast-neq { font-family: "DejaVu Sans", "Segoe UI Symbol", "Apple Symbols", var(--sans); font-size: 2rem; line-height: 1; color: var(--signal); }
.sysfig { margin: 0.5rem 0 0; }
.sysfig-frame { background: var(--panel); border: 1px solid var(--rule); border-radius: var(--radius); padding: 0.75rem 0.5rem; }
.sysdiag { display: block; width: 100%; height: auto; color: var(--ink); }
.sd-tall { display: none; max-width: 420px; margin: 0 auto; }
@media (max-width: 640px) { .sd-wide { display: none; } .sd-tall { display: block; } }
.sysfig figcaption { margin-top: 0.5rem; font-size: 0.9rem; color: var(--muted); max-width: 75ch; }
.sd-box rect, .sd-compare circle, .sd-donebox rect { fill: var(--paper); stroke: currentColor; stroke-width: 1.5; }
.sd-box .icon { color: var(--muted); }
.sd-verifier rect { stroke: var(--accent); stroke-width: 2.5; }
.sd-verifier .icon { color: var(--accent); }
.sd-title { font-family: var(--sans); font-size: 15px; font-weight: 700; fill: currentColor; }
.sd-sub { font-family: var(--sans); font-size: 12.5px; fill: var(--muted); }
.sd-flow { fill: none; stroke: var(--muted); stroke-width: 1.8; }
.sd-label { font-family: var(--sans); font-size: 12.5px; fill: var(--muted); paint-order: stroke; stroke: var(--panel); stroke-width: 5px; stroke-linejoin: round; }
.sd-flow.sd-differ, .sd-flow.sd-fix { stroke: var(--signal); }
.sd-flow.sd-fix { stroke-dasharray: 6 5; stroke-width: 2.2; }
.sd-label.sd-differ, .sd-label.sd-fix { fill: var(--signal); font-weight: 700; }
.sd-flow.sd-same, .sd-flow.sd-test, .sd-flow.sd-done { stroke: var(--ok); }
.sd-flow.sd-test { stroke-dasharray: 6 5; stroke-width: 2.2; }
.sd-label.sd-same, .sd-label.sd-test, .sd-label.sd-done { fill: var(--ok); font-weight: 700; }
.sd-donebox rect { stroke: var(--ok); stroke-width: 2; }
.sd-head-plain { fill: var(--muted); }
.sd-head-bad { fill: var(--signal); }
.sd-head-good { fill: var(--ok); }
.sd-donebox text { fill: var(--ok); }
.stats {
  list-style: none; margin: 1.1rem 0 0; padding: 0;
  display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 0.75rem;
}
.stats li { background: var(--panel); border: 1px solid var(--rule); border-radius: var(--radius); padding: 0.75rem 0.9rem; display: flex; flex-direction: column; gap: 0.2rem; }
.stats .icon-html { margin-bottom: 0.2rem; }
.stats strong { font-family: var(--sans); font-size: 1.7rem; line-height: 1.1; }
.stats span { color: var(--muted); font-size: 0.9rem; }
.next { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0.75rem 1.5rem; }
.next li { font-size: 0.98rem; max-width: 52ch; display: flex; gap: 0.75rem; align-items: flex-start; }
.next li .icon-html { margin-top: 0.15rem; }
.next strong { display: block; font-family: var(--sans); font-size: 1.12rem; margin-bottom: 0.15rem; }
.level-card h3 { font-family: var(--sans); font-weight: 600; font-size: 1.7rem; line-height: 1.12; margin: 0; }
.paper-line { font-family: var(--sans); font-size: 1.15rem; margin: 0.6rem 0 1.4rem; color: var(--muted); }
.paper-line cite { color: var(--ink); }
.lead { font-size: 1.12rem; line-height: 1.6; max-width: 68ch; margin: 0 0 1.75rem; }

.loop {
  list-style: none; margin: 0 0 1.75rem; padding: 0;
  display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 0;
  counter-reset: loop;
  border: 1px solid var(--rule); border-radius: var(--radius);
  background: var(--panel);
  position: relative;
}
.loop li {
  counter-increment: loop;
  padding: 0.9rem 1rem 1rem;
  display: flex; flex-direction: column; gap: 0.2rem;
  position: relative;
  min-width: 0;
}
.loop li + li { border-left: 1px dashed var(--rule); }
.loop li::before {
  content: counter(loop, decimal-leading-zero);
  font-family: var(--mono); font-size: 0.7rem; color: var(--muted); letter-spacing: 0.08em;
}
.loop li + li::after {
  content: "→"; position: absolute; left: -0.6rem; top: calc(50% - 0.6rem);
  font-family: var(--mono); color: var(--muted); background: var(--panel); line-height: 1;
  padding: 0.1rem 0;
}
.loop li:last-child { padding-right: 2.2rem; }
.loop::after {
  content: "↺"; position: absolute; right: 0.7rem; bottom: 0.6rem;
  font-size: 1.2rem; color: var(--muted);
}
.loop strong { font-family: var(--mono); font-size: 0.9rem; }
.loop span { color: var(--muted); font-size: 0.9rem; }
.role { font-size: 1.1rem; max-width: 62ch; margin: 0; }
.role strong { font-family: var(--sans); font-size: 1.3rem; }

/* ---------- level pick ---------- */

.level-grid {
  display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 1.25rem;
  margin-top: 1.5rem;
}
.level-card {
  background: var(--panel); border: 1px solid var(--rule); border-radius: var(--radius);
  padding: 1.25rem; display: flex; flex-direction: column; gap: 0.25rem;
}

.level-card p { margin: 0.25rem 0; }
.level-card .btn-primary { align-self: flex-start; margin-top: auto; }
.level-art {
  border: 1px solid var(--rule); border-radius: var(--radius); margin-bottom: 0.75rem;
  background-color: var(--paper);
  background-image: radial-gradient(var(--grid) 1px, transparent 1px);
  background-size: 14px 14px;
}
.level-art svg { display: block; height: 130px; }
.level-status { font-family: var(--mono); font-size: 0.8rem; color: var(--muted); margin-bottom: 0.75rem !important; }

/* ---------- play ---------- */

.version-head { max-width: 70ch; margin-bottom: 1.25rem; }
.version-head:focus-within { outline: none; }

.strip {
  display: grid; grid-auto-flow: column; grid-auto-columns: minmax(170px, 1fr);
  gap: 0.6rem; overflow-x: auto; padding: 0.25rem 0.15rem 0.6rem;
  margin: 0 -0.15rem 1rem;
  scroll-snap-type: x proximity;
}
.tile {
  cursor: pointer; text-align: left;
  display: flex; flex-direction: column; gap: 0.3rem;
  background: var(--panel); border: 1px solid var(--rule); border-radius: var(--radius);
  padding: 0.5rem 0.6rem 0.6rem; min-width: 0;
  scroll-snap-align: start;
}
.tile:hover { border-color: var(--muted); }
.tile.is-selected { border: 2px solid var(--accent); padding: calc(0.5rem - 1px) calc(0.6rem - 1px) calc(0.6rem - 1px); }
.tile-art { display: block; border-bottom: 1px dashed var(--rule); padding-bottom: 0.25rem; }
.tile-art svg { display: block; height: 64px; }
.tile-title { font-weight: 650; font-size: 0.92rem; line-height: 1.25; }
.tile-blurb {
  display: block; font-size: 0.8rem; line-height: 1.35; color: var(--muted);
  white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
}
.tile-meta {
  display: flex; flex-wrap: wrap; gap: 0.25rem 0.5rem;
  font-family: var(--mono); font-size: 0.7rem; color: var(--muted);
}
.tile-flag {
  border: 1px solid currentColor; border-radius: 3px; padding: 0 0.3rem;
  color: var(--accent); text-transform: uppercase; letter-spacing: 0.06em;
}
.flag-signal { color: var(--signal); }

.bench {
  display: grid; grid-template-columns: minmax(0, 1.4fr) minmax(0, 1fr);
  gap: 1rem; align-items: start;
}
.panel {
  background: var(--panel); border: 1px solid var(--rule); border-radius: var(--radius);
  padding: 1rem; min-width: 0;
}
.card-title { font-size: 1.45rem; }
.card-blurb { margin: 0.35rem 0 0.75rem; max-width: 65ch; }

.netfig {
  margin: 0 0 1rem;
  border: 1px solid var(--rule); border-radius: var(--radius);
  background-color: var(--paper);
  background-image: radial-gradient(var(--grid) 1.2px, transparent 1.2px);
  background-size: 20px 20px;
  padding: 0.25rem 0.25rem 0.5rem;
}
.netfig > svg { display: block; width: 100%; height: auto; }

/* network marks */
.net .link { stroke: var(--muted); stroke-width: 3.5; stroke-linecap: round; }
.net .link.area { stroke-width: 4; }
.net .link.area-0, .swatch .area-0 { stroke: var(--accent); }
.net .link.backbone { stroke-width: 7; }
.net .link.area-1, .swatch .area-1 { stroke: var(--area-1); }
.net .link.area-2, .swatch .area-2 { stroke: var(--area-2); }
.net .link.area-3, .swatch .area-3 { stroke: var(--area-3); }
.net .link.failed, .swatch .link.failed { stroke: var(--muted); stroke-dasharray: 8 7; stroke-width: 3; opacity: 0.55; }
.net .ebgp-edge, .swatch .ebgp-edge { stroke: var(--muted); stroke-width: 2.5; stroke-dasharray: 1 6; stroke-linecap: round; }
.net .client, .swatch .client { fill: none; stroke: var(--accent); stroke-width: 1.6; }
.net .peer, .swatch .peer { fill: none; stroke: var(--accent); stroke-width: 1.4; stroke-dasharray: 4 3; opacity: 0.8; }
.arrowhead { fill: var(--accent); }

.net .node.internal circle { fill: var(--panel); stroke: var(--ink); stroke-width: 2.5; }
.net .node.external rect { fill: var(--paper); stroke: var(--muted); stroke-width: 2; stroke-dasharray: 5 3; }
.net .node text { font-family: var(--mono); font-size: 14px; font-weight: 700; fill: var(--ink); }
.net .node.external text { fill: var(--muted); font-weight: 600; }
.net .node.noroute circle { stroke: var(--signal); stroke-dasharray: 4 3; }
.net .noroute-tag { font-size: 12px !important; fill: var(--signal) !important; }
.net .rid { font-size: 11px !important; font-weight: 600 !important; fill: var(--muted) !important; paint-order: stroke; stroke: var(--paper); stroke-width: 4px; stroke-linejoin: round; }
.net .noroute-tag { paint-order: stroke; stroke: var(--paper); stroke-width: 4px; stroke-linejoin: round; }
.net .ring, .swatch .ring { fill: none; stroke: var(--accent); stroke-width: 3; stroke-dasharray: 5 3; }
.net .route { fill: none; stroke-linecap: round; stroke-linejoin: round; }
/* a wide highlighter band, wider than any link; gold contrasts with the navy backbone,
   the grey links and both page backgrounds */
.net .route-oracle, .swatch .route-oracle { stroke: var(--route-oracle); stroke-width: 14; opacity: 0.6; }
:root:not([data-theme="light"]) .net .route-oracle, :root:not([data-theme="light"]) .swatch .route-oracle { opacity: 0.7; }
.net .route-model, .swatch .route-model { stroke: var(--route-model); stroke-width: 4; stroke-dasharray: 9 6; }
.swatch .route-oracle { stroke-width: 7; }
.swatch .route-model { stroke-width: 3; stroke-dasharray: 6 4; }

.net .chip rect { fill: var(--panel); stroke: var(--rule); stroke-width: 1; }
.net .chip text { font-family: var(--mono); font-size: 12px; font-weight: 700; fill: var(--muted); }
/* OSPF areas: tinted regions that tile the drawing, with a hard border; routers two
   areas share sit on the border between them */
.net .area-region { fill-opacity: 0.12; stroke: var(--muted); stroke-opacity: 0.75; stroke-width: 1.5; stroke-linejoin: round; }
:root[data-theme="light"] .net .area-region { fill-opacity: 0.1; }
.net-mini .area-region { stroke-width: 2.5; }
.area-region.area-0 { fill: var(--accent); }
.area-region.area-1 { fill: var(--area-1); }
.area-region.area-2 { fill: var(--area-2); }
.area-region.area-3 { fill: var(--area-3); }
.swatch .area-region { fill-opacity: 0.22; stroke: var(--muted); stroke-opacity: 0.75; stroke-width: 1; }
.net .area-label { font-family: var(--sans); font-size: 13px; font-weight: 700; }
.net .area-label.area-0 { fill: var(--accent); }
.net .area-label.area-1 { fill: var(--area-1); }
.net .area-label.area-2 { fill: var(--area-2); }
.net .area-label.area-3 { fill: var(--area-3); }
.net .chip-failed rect { stroke-dasharray: 3 2; stroke: var(--muted); }
.net .chip-failed text { fill: var(--muted); }

.net-mini .link { stroke-width: 6; }
.net-mini .link.backbone { stroke-width: 10; }
.net-mini .ebgp-edge { stroke-width: 4; stroke-dasharray: 1 9; }
.net-mini .node.internal circle { stroke-width: 4; }
.net-mini .node.external rect { stroke-width: 3; }

.legend {
  list-style: none; margin: 0.25rem 0.5rem 0; padding: 0;
  display: flex; flex-wrap: wrap; gap: 0.2rem 1rem;
  font-family: var(--sans); font-size: 0.82rem; color: var(--muted);
}
.legend li { display: inline-flex; align-items: center; gap: 0.35rem; }
.swatch { flex: none; }
.swatch line { stroke-width: 3; }
.swatch .backbone { stroke-width: 5; }
.swatch .link:not(.area) { stroke: var(--muted); }

.failures {
  border: 1px solid var(--rule); border-radius: var(--radius);
  margin: 0 0 1rem; padding: 0.5rem 0.75rem 0.6rem;
  display: flex; flex-wrap: wrap; gap: 0.3rem 1.2rem;
}
.failures legend { padding: 0 0.3rem; margin: 0; }
.radio {
  display: inline-flex; align-items: center; gap: 0.45rem; cursor: pointer;
  font-family: var(--mono); font-size: 0.9rem; min-height: 2.25rem;
}
.radio input { width: 1.1rem; height: 1.1rem; accent-color: var(--accent); margin: 0; }
/* rulebook */
.rulebook .label { margin-bottom: 0.3rem; }
.rules-sub { margin: 0 0 0.6rem; font-size: 0.8rem; color: var(--muted); }
.rules-gap { margin: 0.6rem 0 0; font-size: 0.8rem; color: var(--muted); }
.rules { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 0.15rem; }
.rule-item {
  display: grid; grid-template-columns: 1.7rem minmax(0, 1fr); gap: 0.5rem;
  padding: 0.45rem 0.5rem; border-radius: var(--radius); border: 2px solid transparent;
}
.rule-item + .rule-item { border-top: 1px dashed var(--rule); }
.rule-num {
  font-family: var(--mono); font-weight: 800; font-size: 0.85rem;
  width: 1.55rem; height: 1.55rem; display: inline-grid; place-items: center;
  border: 2px solid var(--rule); border-radius: 50%;
}
.rule-text { font-size: 0.94rem; line-height: 1.45; }
p.rule-text { margin: 0; }
.rule-tags { display: inline-flex; flex-wrap: wrap; gap: 0.3rem; margin-left: 0.4rem; vertical-align: 0.1em; }
.rbadge {
  font-family: var(--sans); font-size: 0.72rem; font-weight: 700;
  padding: 0.05rem 0.45rem; border-radius: 999px; border: 1px solid currentColor; line-height: 1.45; white-space: nowrap;
}
.rbadge-new { color: var(--panel); background: var(--accent); border-color: var(--accent); }
.rbadge-changed { color: var(--accent); border-style: dashed; }
.rbadge-decides { color: var(--ink); background: var(--decider-wash); }
.rule-item.is-decider { border: 2px solid var(--ink); background: var(--decider-wash); }
.rule-item.is-decider + .rule-item { border-top-color: transparent; }
.rule-item.is-decider .rule-num { border-color: var(--ink); background: var(--ink); color: var(--panel); }
/* result */
.result { display: flex; flex-direction: column; gap: 1rem; }
.result.is-empty { color: var(--muted); }
.result > .label:first-child { margin: 0; outline: none; text-transform: none; letter-spacing: 0.02em; font-size: 0.8rem; }
.result { gap: 0.75rem; }
.headline {
  margin: 0; font-family: var(--sans); font-size: clamp(1.3rem, 3vw, 1.7rem); line-height: 1.25;
  display: flex; gap: 0.5rem; align-items: baseline;
}
.headline .oicon { font-family: var(--mono); font-weight: 800; }
.is-broke .headline .oicon, .is-broke .headline strong { color: var(--signal); }
.is-held .headline .oicon, .is-held .headline strong { color: var(--ok); }
.answers { display: flex; flex-direction: column; gap: 0.35rem; }
.ans {
  display: grid; grid-template-columns: minmax(7.5rem, max-content) minmax(0, 1fr); gap: 0.2rem 0.9rem;
  padding: 0.4rem 0.6rem; border-left: 6px solid var(--route-oracle); background: var(--paper); border-radius: 0 var(--radius) var(--radius) 0;
}
.ans-model { border-left-style: dashed; border-left-color: var(--route-model); }
.ans-who { font-family: var(--sans); font-size: 0.82rem; font-weight: 700; color: var(--muted); padding-top: 0.1rem; }
.ans-body { min-width: 0; }
.ans-what { font-family: var(--mono); }
.ans-sep { color: var(--muted); }
.ans-why { color: var(--ink); }
.rule-ref {
  font-family: var(--mono); font-size: 0.8rem; font-weight: 800;
  padding: 0 0.3rem; border-radius: 3px; border: 1px solid var(--ink); background: var(--decider-wash);
}
details.more { border-top: 1px dashed var(--rule); padding-top: 0.5rem; }
details.more > summary {
  cursor: pointer; font-size: 0.85rem; font-weight: 700; color: var(--muted);
  min-height: 1.75rem; display: list-item;
}
details.more[open] > summary { margin-bottom: 0.6rem; color: var(--ink); }
.igp-head { margin-top: 0.75rem; }
.placeholder { margin: 0; }
.result h4.label { margin-bottom: 0.4rem; }

.table-wrap { overflow-x: auto; }
table { border-collapse: collapse; width: 100%; font-family: var(--mono); font-size: 0.88rem; }
.rib th, .rib td, .log th, .log td { text-align: left; padding: 0.3rem 0.6rem 0.3rem 0; border-bottom: 1px solid var(--rule); }
.rib thead th, .log thead th { font-size: 0.68rem; text-transform: uppercase; letter-spacing: 0.08em; color: var(--muted); font-weight: 600; border-bottom: 2px solid var(--ink); }
.rib tbody th { font-weight: 700; }
.rib tr.none td { color: var(--signal); font-style: italic; }

/* oracle vs verifier, side by side; stacks when the panel is narrow */
.result-q { margin: 0; font-weight: 700; }
.compare { display: grid; grid-template-columns: repeat(auto-fit, minmax(13.5rem, 1fr)); gap: 0.9rem 1rem; }
.side { min-width: 0; }
.answer { margin: 0 0 0.35rem; font-family: var(--mono); font-size: 0.85rem; }
.answer-k { color: var(--muted); }
.cmp-note { margin: 0.4rem 0 0; font-size: 0.88rem; color: var(--signal); font-weight: 600; }
.cmp { font-size: 0.82rem; }
.cmp th, .cmp td { padding-left: 0.35rem; padding-right: 0.4rem; }
.cmp td[colspan] { white-space: nowrap; }
.cmp tr.is-diff > * { background: var(--signal-wash); }
.cmp tr.is-q > * { font-weight: 700; border-top: 2px solid var(--accent); border-bottom: 2px solid var(--accent); }
.cmp tr.is-q > th { box-shadow: inset 3px 0 0 var(--accent); }
.cmp tr.none td { color: var(--muted); }
.cmp tr.none.is-diff td { color: var(--signal); }
.cmp tbody th { white-space: nowrap; }
.qtag, .dtag {
  display: inline-block; margin-left: 0.3rem; padding: 0 0.25rem; border-radius: 3px;
  font-size: 0.68rem; font-weight: 800; line-height: 1.35; vertical-align: 0.1em;
}
.qtag { color: var(--panel); background: var(--accent); }
.dtag { color: var(--signal); border: 1px solid var(--signal); }
.cmp-key { margin: 0.5rem 0 0; font-family: var(--mono); font-size: 0.72rem; color: var(--muted); }
.cmp-key .qtag, .cmp-key .dtag { margin-left: 0; }

.diff-fig { margin: 0 0 1rem; min-width: 0; }
.diff {
  margin: 0; overflow-x: auto; max-width: 100%;
  font-family: var(--mono); font-size: 0.8rem; line-height: 1.55;
  background: var(--paper); border: 1px solid var(--rule); border-radius: var(--radius);
  padding: 0.75rem 0;
}
.diff code { background: none; border: 0; padding: 0; font-size: inherit; display: block; min-width: max-content; }
.diff span { display: block; padding: 0 0.9rem; white-space: pre; }
.diff .add { background: var(--ok-wash); color: var(--ink); }
.diff .add::first-letter { color: var(--ok); font-weight: 800; }
.diff .del { background: var(--signal-wash); color: var(--ink); }
.diff .del::first-letter { color: var(--signal); font-weight: 800; }
.diff .gap { color: var(--muted); }
.found { font-family: var(--mono); font-size: 0.88rem; margin: 0; }
.found-you { font-weight: 700; }
.note {
  margin: 1.75rem 0; padding: 1rem 1.25rem;
  border-left: 4px solid var(--accent); background: var(--panel);
  border-radius: 0 var(--radius) var(--radius) 0;
}
.note p:last-child { margin: 0; font-size: 1.05rem; }
.endtext { font-family: var(--sans); font-size: 1.3rem; line-height: 1.45; max-width: 60ch; }

/* ---------- story ---------- */

.progress { margin: 0 0 1.25rem; }
.pgroups { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 0.5rem; }
.pdot {
  all: unset; box-sizing: border-box; cursor: pointer; display: block; width: 100%;
  padding: 0.45rem 0.3rem 0.25rem; border-top: 5px solid var(--rule);
  font-size: 0.85rem; color: var(--muted);
  white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
}
.pdot:hover { color: var(--ink); border-top-color: var(--muted); }
.pdot.is-done { border-top-color: var(--muted); }
.pdot.is-current { border-top-color: var(--accent); color: var(--ink); font-weight: 700; }
.pdot:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }

.step-head { max-width: 75ch; margin-bottom: 1.25rem; }
.step-head h1 { outline: none; }
.step-lead { font-size: 1.08rem; margin: 0.6rem 0 0; }
.story > .bench, .story > .panel, .explore > .bench, .explore > .panel { margin-top: 1rem; }
.storynav {
  display: flex; flex-wrap: wrap; gap: 0.75rem; align-items: center;
  margin-top: 1.5rem; padding-top: 1rem; border-top: 1px solid var(--rule);
}
.storynav .btn-primary { margin-left: auto; }

/* rules */
.rule-item.is-mistake { border: 2px solid var(--signal); background: var(--signal-wash); }
.rule-item.is-mistake + .rule-item { border-top-color: transparent; }
.rule-item.is-mistake .rule-num { border-color: var(--signal); background: var(--signal); color: var(--panel); }
.rbadge-mistake { color: var(--panel); background: var(--signal); border-color: var(--signal); }
.rule-wrong { display: block; margin-top: 0.2rem; font-size: 0.88rem; line-height: 1.4; color: var(--signal); }
.rule-wrong strong, .rules-missing strong { font-weight: 700; }
.rules-missing { margin: 0.6rem 0 0; padding: 0.4rem 0.6rem; font-size: 0.88rem; color: var(--signal); border: 1px dashed var(--signal); border-radius: var(--radius); }
.rules-other { margin: 0.7rem 0 0; font-size: 0.86rem; color: var(--muted); }
.rules-other summary { cursor: pointer; }
.rules-other ul { margin: 0.4rem 0 0; padding-left: 1.1rem; }
.rules-other li { margin: 0.25rem 0; }
.rules-other strong { font-weight: 600; }
.rules-other .rules-other-lead { color: var(--ink); }
.net .value-tag {
  font-family: var(--mono); font-size: 12px; font-weight: 800; fill: var(--signal);
  paint-order: stroke; stroke: var(--paper); stroke-width: 4px; stroke-linejoin: round;
}

/* the two answers, each on a faint copy of the network */
.answer-figs { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0.9rem; margin: 0.6rem 0 0.9rem; }
.answer-fig { margin: 0; border: 1px solid var(--rule); border-radius: var(--radius); background: var(--paper); padding: 0.5rem 0.5rem 0.25rem; min-width: 0; }
.answer-fig.is-ref { border-top: 5px solid var(--route-oracle); }
.answer-fig.is-model { border-top: 5px dashed var(--route-model); }
.answer-fig figcaption { display: flex; flex-wrap: wrap; gap: 0.1rem 0.5rem; align-items: baseline; padding: 0 0.25rem; }
.af-who { font-family: var(--sans); font-size: 0.82rem; font-weight: 700; color: var(--muted); }
.af-what { font-weight: 700; }
.answer-fig.is-hidden .af-what { color: var(--muted); font-weight: 400; font-style: italic; }
.answer-fig > svg { display: block; width: 100%; height: auto; max-height: 240px; }
.net-answer .link { opacity: 0.8; }
.net-answer .ebgp-edge { opacity: 0.5; }
.route-arrow { fill: none; stroke-width: 4.5; stroke-linecap: round; }
.route-arrow-oracle { stroke: var(--route-oracle-ink); }
.route-arrow-model { stroke: var(--route-model); }
.route-head-oracle { fill: var(--route-oracle-ink); }
.route-head-model { fill: var(--route-model); }
.net-unknown { font-family: var(--sans); font-size: 110px; font-weight: 700; fill: var(--muted); opacity: 0.35; }

/* quiz and reveal */
.normally { margin: 0 0 0.4rem; font-size: 1.05rem; }
.quiz-q { margin: 0 0 0.75rem; font-weight: 700; font-size: 1.12rem; }
.choice-buttons { display: flex; flex-wrap: wrap; gap: 0.6rem; }
.btn-choice {
  cursor: pointer; border-radius: var(--radius); font-weight: 700; line-height: 1.2;
  border: 1px solid var(--rule-strong); min-height: 2.75rem; padding: 0.7rem 1.2rem;
  font-family: var(--mono); font-size: 1rem; background: var(--panel);
}
.btn-choice:hover:not(:disabled) { border-color: var(--accent); }
.btn-choice[aria-pressed="true"] { background: var(--accent); border-color: var(--accent); color: var(--on-accent); }
.btn-choice:disabled { cursor: default; opacity: 0.55; }
.btn-choice[aria-pressed="true"]:disabled { opacity: 0.9; }
.just-show { margin: 0.75rem 0 0; font-size: 0.92rem; }
.reveal-box { display: flex; flex-direction: column; gap: 0.7rem; border-width: 2px; }
.reveal-box.is-broke { border-color: var(--signal); }
.reveal-box.is-held { border-color: var(--ok); }
.reveal-box .headline { outline: none; }
.guessed { margin: 0; font-weight: 700; font-size: 1.08rem; }
.guessed.right { color: var(--ok); }
.guessed.wrong { color: var(--muted); }
.why { display: flex; flex-direction: column; gap: 0.4rem; }
.why-row {
  margin: 0; padding: 0.5rem 0.7rem; font-size: 1.02rem; background: var(--paper);
  border-left: 6px dashed var(--route-model); border-radius: 0 var(--radius) var(--radius) 0;
}
.why-ref { border-left: 6px solid var(--route-oracle); }

/* the fix */
.fix, .closing { border-top: 1px dashed var(--rule); padding-top: 0.7rem; }
.fix .label { margin-bottom: 0.5rem; }
.fix .found { margin: 0.2rem 0 0.6rem; font-family: var(--sans); font-size: 0.9rem; color: var(--muted); }
.rchanges { list-style: none; margin: 0 0 0.5rem; padding: 0; display: flex; flex-direction: column; gap: 0.6rem; }
.rchange { display: grid; grid-template-columns: 1.7rem minmax(0, 1fr); gap: 0.5rem; align-items: start; }
.rchange-body p { margin: 0; display: grid; grid-template-columns: 4rem minmax(0, 1fr); gap: 0.6rem; align-items: baseline; padding: 0.35rem 0.6rem; }
.rbefore { background: var(--signal-wash); border-radius: var(--radius) var(--radius) 0 0; }
.rafter { background: var(--ok-wash); border-radius: 0 0 var(--radius) var(--radius); }
.rwho { font-size: 0.78rem; font-weight: 700; color: var(--muted); }
.rnone { color: var(--muted); font-style: italic; }
.rafter.still-wrong { background: var(--decider-wash); }
.still-note { display: block; font-size: 0.85rem; font-weight: 600; color: var(--signal); }
.howto { margin: 0.9rem 0 0; background: var(--panel); border: 1px solid var(--rule); border-radius: var(--radius); padding: 0.55rem 0.85rem; max-width: 75ch; }
.howto > summary { cursor: pointer; font-weight: 700; min-height: 1.75rem; }
.howto ul { margin: 0.4rem 0 0.2rem; padding-left: 1.1rem; display: flex; flex-direction: column; gap: 0.3rem; font-size: 0.95rem; }
.closing .endtext { margin: 0; }
.closing .note { margin: 1rem 0 0; }

/* explorer */
.explore-bar { display: flex; flex-wrap: wrap; gap: 0.75rem 1rem; align-items: center; justify-content: space-between; margin-top: 1rem; }
.vtabs { display: inline-flex; border: 1px solid var(--rule-strong); border-radius: 999px; overflow: hidden; }
.vtab { all: unset; cursor: pointer; padding: 0.5rem 1rem; font-size: 0.9rem; font-weight: 600; }
.vtab + .vtab { border-left: 1px solid var(--rule-strong); }
.vtab:hover { background: var(--panel); }
.vtab[aria-pressed="true"] { background: var(--accent); color: var(--on-accent); }
.vtab:focus-visible { outline: 3px solid var(--accent); outline-offset: -3px; }

/* confetti for a right guess */
.confetti { position: fixed; inset: 0; pointer-events: none; overflow: hidden; z-index: 50; }
.confetti span { position: absolute; display: block; margin: -5px 0 0 -4px; border-radius: 2px; }

/* ---------- footer ---------- */

.colophon { border-top: 1px solid var(--rule); margin-top: 3rem; }
.colophon-inner {
  display: flex; flex-direction: column; gap: 0.6rem; align-items: center; text-align: center;
  padding-top: 1.5rem; padding-bottom: 1.75rem;
}
.colophon-note { margin: 0; font-size: 0.88rem; color: var(--muted); max-width: 70ch; }
.colophon-links { display: flex; flex-wrap: wrap; justify-content: center; gap: 0.5rem 1.25rem; font-size: 0.88rem; }
.theme-toggle { all: unset; cursor: pointer; color: var(--accent); }
.theme-toggle:hover { text-decoration: underline; }
.theme-toggle:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }
body.kiosk .colophon-links { display: none; }
body.kiosk .wrap { max-width: 1500px; }

/* ---------- narrow ---------- */

@media (max-width: 760px) {
  .bench { grid-template-columns: minmax(0, 1fr); }
  .rchange-body p { grid-template-columns: minmax(0, 1fr); gap: 0.1rem; }
  .storynav .btn-primary { margin-left: 0; width: 100%; }
  .ans { grid-template-columns: minmax(0, 1fr); }
  .level-grid { grid-template-columns: minmax(0, 1fr); }
  .loop { grid-template-columns: minmax(0, 1fr); }
  .stats, .next { grid-template-columns: minmax(0, 1fr); }
  .answer-figs { grid-template-columns: minmax(0, 1fr); }
  .loop li + li { border-left: 0; border-top: 1px dashed var(--rule); }
  .loop li + li::after { content: "↓"; left: auto; right: 1rem; top: -0.65rem; padding: 0 0.2rem; }
  .loop li:last-child { padding-right: 1rem; }
  .strip { grid-auto-columns: minmax(150px, 46%); }
  /* keep router names and link labels legible when the 600-unit drawing shrinks */
  .netfig .node > * { scale: 1.3; }
  .netfig .net .area-label { font-size: 17px; }
  .netfig .ringg > * { scale: 1.3; }
  .netfig .chip > * { scale: 1.15; }
  .netfig .net .link { stroke-width: 5; }
  .netfig .net .link.backbone { stroke-width: 9; }
  .netfig .net .client { stroke-width: 2.2; }
  .netfig .net .noroute-tag { scale: 1.2; }
}


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

/* ---------- the verifier, speaking ---------- */

.says { display: flex; align-items: center; gap: 0.4rem; margin: 0.6rem 0 0.8rem; }
.mascot { flex: none; width: 80px; height: 110px; }
.mascot .m-line { fill: none; stroke: var(--ink); stroke-width: 3; stroke-linecap: round; stroke-linejoin: round; }
.mascot .m-thin { stroke-width: 2; }
.mascot .m-head { fill: var(--panel); stroke: var(--route-model); stroke-width: 3; }
.mascot .m-eye, .mascot .m-mouth { fill: var(--ink); }
.mascot .m-hat { fill: none; stroke: var(--ink); stroke-width: 4; stroke-linecap: square; }
.mascot .m-band { stroke: var(--route-model); }
.mascot .m-cape { fill: color-mix(in srgb, var(--route-model) 30%, transparent); stroke: var(--route-model); stroke-width: 1.5; stroke-linejoin: round; }
.mascot .m-glass circle { fill: color-mix(in srgb, var(--accent) 22%, transparent); stroke: var(--ink); stroke-width: 2.5; }
.mascot .m-glass path { fill: none; stroke: var(--ink); stroke-width: 2.5; stroke-linecap: round; }
.mascot .m-mark { font-family: var(--sans); font-size: 18px; font-weight: 800; fill: var(--route-model); }
.says-learned { margin: 0.9rem 0 0.4rem; }
.bubble {
  position: relative; margin: 0 0 0 0.9rem; padding: 0.7rem 0.95rem;
  background: var(--paper); border: 2px solid var(--ink); border-radius: 18px;
  font-size: 1rem; font-weight: 600; line-height: 1.4; color: var(--ink); max-width: 34rem;
}
/* the tail, pointing at the robot: an outlined triangle, then a filled one over it */
.bubble::before, .bubble::after { content: ""; position: absolute; top: 50%; border-style: solid; border-color: transparent; }
.bubble::before { left: -16px; margin-top: -10px; border-width: 10px 16px 10px 0; border-right-color: var(--ink); }
.bubble::after { left: -12px; margin-top: -8px; border-width: 8px 13px 8px 0; border-right-color: var(--paper); }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip-path: inset(50%); white-space: nowrap; }
@media (max-width: 520px) {
  .mascot { width: 58px; height: 80px; }
  .bubble { font-size: 0.92rem; }
}