:root {
  --halo: rgba(240, 246, 252, 0.62);
  --halo-edge: rgba(240, 246, 252, 0.22);
  --veil: rgba(225, 236, 246, 0.06);
  /* Winter sky at the top of the page fading to snow at the bottom. */
  --sky: #CCDAE8;
  --paper: #E9F0F6;
  --plate: #FBFDFF;
  --ink: #142640;
  --ink-soft: #4A5E78;
  --line: rgba(20, 38, 64, 0.14);
  --ice: #3C78B4;
  --snow: #FFFFFF;
  /* Snow against a bright sky reads blue-grey, not white. */
  --snow-shade: #A3B9D1;
  --font: "Bricolage Grotesque", ui-sans-serif, system-ui, sans-serif;
  /* Display face for names and titles: rounded, like the packed snow in the background art. */
  --display: "Baloo 2", "Bricolage Grotesque", system-ui, sans-serif;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root {
    --halo: rgba(13, 22, 38, 0.6);
    --halo-edge: rgba(13, 22, 38, 0.3);
    --veil: rgba(8, 14, 30, 0.45);
    --sky: #070E1A;
    --paper: #12203A;
    --plate: #172946;
    --ink: #E8F0F8;
    --ink-soft: #9DB0C8;
    --line: rgba(232, 240, 248, 0.14);
    --ice: #A8D2F0;
    --snow: #EAF4FF;
    --snow-shade: #EAF4FF;
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }

html, body {
  height: 100%;
  margin: 0;
  overflow: hidden;
  color: var(--ink);
  font-family: var(--font);
  -webkit-font-smoothing: antialiased;
}

#stage {
  position: fixed;
  inset: 0;
  touch-action: manipulation;
  user-select: none;
  -webkit-user-select: none;
}

/* Only the root gets the fallback sky; body stays transparent so the backdrop shows. */
html { background: linear-gradient(180deg, var(--sky), var(--paper)) fixed var(--paper); }

#snow-back,
#snow-front,
#flake {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}

/* The atmosphere is decoration only: clicks pass straight through it. */
#snow-back,
#snow-front { pointer-events: none; }

/* Out-of-focus flakes in front step back while a card is open. */
#snow-front { transition: opacity 0.6s; }
body.is-reading #snow-front { opacity: 0.25; }

/* The snowy field behind everything. It drifts a little as you zoom (set from main.js), and a
   frosted glow behind the flake keeps its arms readable against the sky. */
#backdrop {
  position: fixed;
  inset: -4%;
  z-index: -1;
  /* Shown until (or instead of, without WebGL) the 3D landscape. */
  background: linear-gradient(180deg, var(--sky), var(--paper));
  transform-origin: 50% 58%;
  transform: scale(calc(var(--intro-scale, 1.1) * var(--drift-scale, 1)));
  /* A slight defocus behind the content; light enough that the wildlife still reads. */
  filter: blur(var(--intro-blur, 0.7px));
  will-change: transform, filter;
}

#intro-flake {
  position: fixed;
  left: 0;
  top: 0;
  z-index: 1;
  width: 64px;
  height: 64px;
  pointer-events: none;
  visibility: hidden;
}

#intro-flake svg { display: block; width: 100%; height: 100%; overflow: visible; }
#intro-flake .arms { fill: none; stroke: #fff; stroke-width: 2.6; stroke-linecap: round; }
#intro-flake .core { fill: #fff; stroke: none; }
#intro-flake svg { filter: drop-shadow(0 0 1.2px rgba(40, 90, 150, 0.55)) drop-shadow(0 0 6px rgba(255, 255, 255, 0.7)); }

/* While the opening shot plays, the page chrome waits. */
.top, .hint, .zoom-out { transition: opacity 0.8s; }
body.is-intro .top,
body.is-intro .hint { opacity: 0; pointer-events: none; }

/* The 3D winter landscape (landscape.js) renders here. */
#backdrop .landscape-canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  display: block;
}

/* A frosted glow behind the flake keeps its arms readable against the scene. */
#backdrop::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    radial-gradient(ellipse 46% 58% at 50% 50%, var(--halo) 0%, var(--halo-edge) 55%, transparent 80%),
    linear-gradient(var(--veil), var(--veil));
}

@media (max-width: 900px) {
  #backdrop::after {
    background:
      radial-gradient(ellipse 60% 46% at 50% 50%, var(--halo) 0%, var(--halo-edge) 55%, transparent 80%),
      linear-gradient(var(--veil), var(--veil));
  }
}

#labels {
  position: absolute;
  inset: 0;
  pointer-events: none;
}

/* ---------- labels on hexagons ---------- */

.node-label {
  position: absolute;
  left: 0;
  top: 0;
  padding: 0.1em 0.25em;
  border: 0;
  background: none;
  color: var(--ink);
  font: inherit;
  font-size: var(--label-base, 16px);
  line-height: 1.05;
  white-space: nowrap;
  text-align: center;
  text-shadow: 0 0 0.1em var(--plate), 0 0 0.25em var(--plate);
  cursor: pointer;
  visibility: hidden;
}

.node-label.is-focus { cursor: default; }

/* inline-block so a two-line title measures as its longest line */
.node-label .t {
  display: inline-block;
  font-family: var(--display);
  font-size: 1.05em;
  font-weight: 600;
  letter-spacing: 0;
  line-height: 1;
}

.node-label:focus-visible {
  outline: 2px solid var(--ink);
  outline-offset: 4px;
  border-radius: 2px;
}

.node-label .b:empty { display: none; }

.node-label .b {
  position: absolute;
  top: calc(100% + 0.7em);
  left: 50%;
  transform: translateX(-50%);
  width: max-content;
  max-width: var(--blurb-width, 240px);
  font-size: var(--blurb-size, 15px);
  font-weight: 400;
  font-stretch: 100%;
  letter-spacing: 0;
  line-height: 1.4;
  white-space: normal;
  text-wrap: balance;
  color: var(--ink-soft);
  text-shadow: none;
}

.node-label.is-root .t { font-size: 1.12em; font-weight: 700; letter-spacing: -0.01em; }

/* ---------- leaf cards ---------- */

/* The frame covers the card's hexagon and moves with it; it never takes clicks itself. */
.card-frame {
  position: absolute;
  left: 0;
  top: 0;
  visibility: hidden;
  pointer-events: none;
}

.card {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  overflow: auto;
  padding: 8px 12px 24px;
  background: transparent;
  color: var(--ink);
  /* --k shrinks a card's text so it can fit inside its hexagon. */
  font-size: calc(var(--k, 1) * 16px);
  scrollbar-width: thin;
  user-select: text;
  -webkit-user-select: text;
  outline: none;
}

/* Hexagon layout: two shaped wedges push every line in to the plate's slanted edges, and a
   spacer centers the text vertically. Long cards fall back to a scrolling column. */
.card-shape,
.card-spacer { display: none; }

.card.is-hex { padding: 0; overflow: hidden; }
.card.is-hex .card-shape { display: block; }
.card.is-hex .card-spacer { display: block; }
.card-shape.l { float: left; }
.card-shape.r { float: right; }

.card.is-flat .card-shape.l { shape-outside: polygon(0 0, 100% 0, 0 50%, 100% 100%, 0 100%); }
.card.is-flat .card-shape.r { shape-outside: polygon(0 0, 100% 0, 100% 100%, 0 100%, 100% 50%); }
.card.is-pointy .card-shape.l { shape-outside: polygon(0 0, 100% 0, 0 25%, 0 75%, 100% 100%, 0 100%); }
.card.is-pointy .card-shape.r { shape-outside: polygon(0 0, 100% 0, 100% 100%, 0 100%, 100% 75%, 100% 25%); }

.card.is-hex p,
.card.is-hex ul,
.card.is-hex ol { max-width: none; }

.card-frame.is-live .card { pointer-events: auto; }

/* While there's more below, the bottom edge fades out. */
.card.has-more { mask-image: linear-gradient(to bottom, #000 calc(100% - 40px), transparent); }

/* On larger screens the scrollbar runs along the hexagon's right-hand edges instead. */
@media (min-width: 560px) {
  .card { scrollbar-width: none; }
  .card::-webkit-scrollbar { display: none; }
}

.card-track {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  overflow: visible;
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.3s;
}

.card-frame.is-scrollable .card-track { opacity: 1; }
.card-track path { fill: none; stroke-linecap: round; stroke-linejoin: round; }
.card-track .rail { stroke: color-mix(in srgb, var(--hue) 22%, transparent); stroke-width: 4; }
.card-track .thumb { stroke: var(--hue); stroke-width: 6; }
.card-track .hit { stroke: transparent; stroke-width: 24; cursor: pointer; }
.card-frame.is-live.is-scrollable .card-track .hit { pointer-events: stroke; }

.card h1 {
  margin: 0 0 0.25em;
  font-family: var(--display);
  font-size: 2.5em;
  font-weight: 700;
  letter-spacing: -0.01em;
  line-height: 1.05;
}

.card h2,
.card h3 {
  margin: 1.2em 0 0.35em;
  font-family: var(--display);
  font-weight: 600;
  letter-spacing: 0;
  line-height: 1.15;
}

.card h2 { font-size: 1.3em; }
.card h3 { font-size: 1.15em; }

.card ul:not(.tags, .links),
.card ol {
  max-width: 60ch;
  margin: 0 0 0.9em;
  padding-left: 1.3em;
  font-size: 0.97em;
  line-height: 1.55;
}

.card ul:not(.tags, .links) { list-style: none; }

/* Loose lists wrap each item in a paragraph; keep it on the bullet's line. */
.card li > p { display: inline; margin: 0; }

.card ul:not(.tags, .links) > li::before {
  content: "";
  display: inline-block;
  width: 0.55em;
  height: 0.48em;
  margin: 0 0.6em 0 -1.15em;
  background: var(--hue);
  clip-path: polygon(25% 0, 75% 0, 100% 50%, 75% 100%, 25% 100%, 0 50%);
}

.card img {
  display: block;
  max-width: 100%;
  height: auto;
  margin: 1em 0;
}

.card code {
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
  font-size: 0.9em;
  padding: 0.1em 0.3em;
  background: color-mix(in srgb, var(--hue) 10%, var(--plate));
}

.card pre {
  overflow: auto;
  padding: 12px 14px;
  font-size: 0.875em;
  line-height: 1.5;
  background: color-mix(in srgb, var(--hue) 8%, var(--plate));
}

.card pre code { padding: 0; background: none; }

.card blockquote {
  margin: 1em 0;
  padding-left: 1em;
  border-left: 3px solid var(--hue);
  color: var(--ink-soft);
}

.card hr {
  border: 0;
  border-top: 1px solid var(--line);
  margin: 1.5em 0;
}

.card table { border-collapse: collapse; font-size: 0.94em; margin: 1em 0; }
.card th, .card td { padding: 6px 10px; border-bottom: 1px solid var(--line); text-align: left; }

.card .card-status { color: var(--ink-soft); }

.card .meta {
  margin: 0 0 1.3em;
  font-size: 0.94em;
  font-weight: 560;
  color: var(--ink-soft);
}

.card .meta em { font-style: normal; }

.card .meta::before,
.card .tags li::before {
  content: "";
  display: inline-block;
  margin-right: 0.55em;
  width: 0.7em;
  height: 0.6em;
  background: var(--hue);
  clip-path: polygon(25% 0, 75% 0, 100% 50%, 75% 100%, 25% 100%, 0 50%);
}

.card p {
  max-width: 60ch;
  margin: 0 0 0.8em;
  font-size: 0.97em;
  line-height: 1.55;
}

.card .tags,
.card .links {
  list-style: none;
  padding: 0;
  margin: 1.4em 0 0;
  line-height: 1.9;
}

.card .tags li,
.card .links li {
  display: inline-block;
  margin-right: 1.3em;
  white-space: nowrap;
}

.card .tags { font-size: 0.9em; color: var(--ink-soft); }
.card .tags li::before { width: 0.55em; height: 0.48em; margin-right: 0.45em; }

.card .links { font-weight: 560; }
.card p + .links, .card .tags + .links, .card .tags + p { margin-top: 1.2em; }

.card a {
  color: var(--ink);
  text-decoration: underline;
  text-decoration-color: var(--hue);
  text-decoration-thickness: 2px;
  text-underline-offset: 4px;
}

.card a:hover { text-decoration-thickness: 3px; }
.card a:focus-visible { outline: 2px solid var(--ink); outline-offset: 3px; }

@media (max-width: 559px) {
  .card {
    padding: 22px 20px 26px;
    background: var(--plate);
    border-top: 4px solid var(--hue);
    box-shadow: 0 1px 0 var(--line), 0 0 0 1px var(--line);
  }
}

/* ---------- chrome ---------- */

.top {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 2;
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 16px;
  padding: 16px 20px;
  pointer-events: none;
}

.top > * { pointer-events: auto; }

.crumbs ol {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  margin: 0;
  padding: 0;
  list-style: none;
  font-size: 15px;
}

.crumbs li + li::before {
  content: "/";
  margin: 0 0.45em;
  color: var(--ink-soft);
}

.crumbs a {
  display: inline-block;
  padding: 6px 2px;
  color: var(--ink-soft);
  text-decoration: none;
}

.crumbs a:hover { color: var(--ink); }
.crumbs a[aria-current] { color: var(--ink); font-weight: 620; }
.crumbs a:focus-visible { outline: 2px solid var(--ink); outline-offset: 2px; }

@media (max-width: 559px) {
  .top { padding: 12px 12px; }
  .crumbs li:not(:nth-last-child(-n + 2)) { display: none; }
  .crumbs li:nth-last-child(2)::before { content: none; }
}

/* Buttons are stretched hexagons to echo the grid. */
.btn {
  font: inherit;
  font-size: 14px;
  font-weight: 560;
  padding: 9px 20px;
  border: 0;
  background: var(--plate);
  color: var(--ink);
  cursor: pointer;
  clip-path: polygon(12px 0, calc(100% - 12px) 0, 100% 50%, calc(100% - 12px) 100%, 12px 100%, 0 50%);
}

.btn:hover { background: color-mix(in srgb, var(--plate) 70%, var(--ink) 8%); }
.btn:focus-visible { background: var(--ink); color: var(--paper); outline: none; }

.zoom-out {
  position: fixed;
  right: 20px;
  bottom: 16px;
  z-index: 2;
}

.hint {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 18px;
  margin: 0;
  padding: 0 120px;
  text-align: center;
  font-size: 14px;
  color: var(--ink-soft);
  pointer-events: none;
  transition: opacity 0.6s;
}

.hint.is-gone { opacity: 0; }

.status {
  position: fixed;
  top: 60px;
  left: 50%;
  z-index: 3;
  transform: translateX(-50%);
  width: max-content;
  max-width: calc(100vw - 32px);
  margin: 0;
  padding: 10px 16px;
  font-size: 14.5px;
  background: var(--ink);
  color: var(--paper);
}

/* On small screens the center slot is too tight for blurbs, so they show here instead. */
.caption {
  display: none;
  position: fixed;
  left: 16px;
  right: 16px;
  bottom: 46px;
  margin: 0;
  font-size: 15px;
  line-height: 1.45;
  text-align: center;
  text-wrap: balance;
  color: var(--ink-soft);
  pointer-events: none;
}

@media (max-width: 559px) {
  .hint { padding: 0 16px; bottom: 56px; }
  .caption:not(:empty) { display: block; bottom: 88px; }
  .zoom-out { right: 12px; bottom: 12px; }
}

/* ---------- outline dialog ---------- */

.outline {
  width: min(520px, calc(100vw - 32px));
  max-height: min(80vh, 720px);
  padding: 24px 28px 28px;
  border: 0;
  background: var(--plate);
  color: var(--ink);
}

.outline::backdrop {
  background: color-mix(in srgb, var(--paper) 70%, transparent);
  backdrop-filter: blur(4px);
}

.outline-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 12px;
}

.outline h2 {
  margin: 0;
  font-family: var(--display);
  font-size: 28px;
  font-weight: 700;
}

.outline .btn { background: var(--paper); }

.outline ul {
  list-style: none;
  margin: 0;
  padding: 0 0 0 18px;
}

.outline > nav > ul { padding: 0; }

.outline li { margin: 2px 0; }

.outline-credits {
  margin: 20px 0 0;
  padding-top: 12px;
  border-top: 1px solid var(--line);
  font-size: 12.5px;
  line-height: 1.5;
  color: var(--ink-soft);
}

.outline-credits a { color: inherit; }

.outline .expand {
  width: 26px;
  height: 26px;
  margin-left: 6px;
  border: 0;
  background: none;
  color: var(--ink-soft);
  font: inherit;
  font-size: 18px;
  line-height: 1;
  cursor: pointer;
}

.outline .expand:hover { color: var(--ink); }
.outline .expand:focus-visible { outline: 2px solid var(--ink); outline-offset: 1px; }

.outline a {
  display: inline-flex;
  align-items: center;
  gap: 0.5em;
  padding: 4px 0;
  color: var(--ink);
  text-decoration: none;
  font-size: 16px;
}

.outline a::before {
  content: "";
  width: 0.62em;
  height: 0.54em;
  background: var(--hue, var(--ink));
  clip-path: polygon(25% 0, 75% 0, 100% 50%, 75% 100%, 25% 100%, 0 50%);
}

.outline a:hover { text-decoration: underline; text-decoration-color: var(--hue, var(--ink)); text-underline-offset: 3px; }
.outline a:focus-visible { outline: 2px solid var(--ink); outline-offset: 2px; }
.outline > nav > ul > li > a { font-weight: 620; }

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

.noscript {
  position: fixed;
  inset: 0;
  display: grid;
  place-items: center;
  margin: 0;
}