/* ==========================================================================
   Explore — an AI safety wiki · "aurora glass"
   Frosted panels floating over a slow ambient aurora field.
   Display/UI and prose: Source Serif 4 · Math: KaTeX
   ========================================================================== */

@font-face {
  font-family: "Source Serif 4";
  src: url("typefaces/source-serif-4-latin-wght-normal.woff2") format("woff2-variations");
  font-weight: 200 900;
  font-style: normal;
  font-display: swap;
}

/* ---- tokens ---------------------------------------------------------- */

:root {
  color-scheme: light dark;
  --sans: "Source Serif 4", Georgia, "Iowan Old Style", serif;
  --serif: "Source Serif 4", Georgia, "Iowan Old Style", serif;
  --mono: ui-monospace, "Cascadia Code", Consolas, monospace;

  --bg0: #eef1fa;
  --fg: #1a2036;
  --muted: #545f80;
  --faint: #7f88a8;
  --stroke: rgba(26, 32, 62, 0.10);
  --stroke-strong: rgba(26, 32, 62, 0.20);
  --panel: rgba(255, 255, 255, 0.58);
  --card: rgba(255, 255, 255, 0.52);
  --chip: rgba(255, 255, 255, 0.5);
  --hover: rgba(26, 32, 62, 0.05);
  --header-bg: rgba(243, 245, 252, 0.6);
  --link: #0b63a5;
  --link-visited: #6d28d9;
  --acc-a: #0891b2;
  --acc-b: #6366f1;
  --acc-c: #c026d3;
  --hero-grad: linear-gradient(95deg, #312e81, #0e7490 55%, #a21caf);
  --panel-shadow: 0 18px 50px rgba(60, 70, 130, 0.16), inset 0 1px 0 rgba(255, 255, 255, 0.75);
  --card-shadow: 0 2px 10px rgba(60, 70, 130, 0.06);
  --dialog-bg: rgba(250, 251, 255, 0.82);
  --noise-opacity: 0.25;
  --k-concept: #b45309;
  --k-edge: #047857;
  --k-theme: #4f46e5;
  --k-supertheme: #a21caf;
  --k-superedge: #4d7c0f;
  --k-tissue: #0e7490;
  --k-story: #be123c;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg0: #0a0d1c;
    --fg: #e9ecf8;
    --muted: #9aa3c0;
    --faint: #6e779a;
    --stroke: rgba(255, 255, 255, 0.08);
    --stroke-strong: rgba(255, 255, 255, 0.17);
    --panel: rgba(20, 25, 48, 0.52);
    --card: rgba(255, 255, 255, 0.04);
    --chip: rgba(255, 255, 255, 0.055);
    --hover: rgba(255, 255, 255, 0.055);
    --header-bg: rgba(10, 13, 28, 0.55);
    --link: #8fd7fc;
    --link-visited: #c4b5fd;
    --acc-a: #67e8f9;
    --acc-b: #8b95f8;
    --acc-c: #f0abfc;
    --hero-grad: linear-gradient(95deg, #eaf6ff, #8fe8ff 35%, #a8b3ff 65%, #f2b8ff);
    --panel-shadow: 0 24px 70px rgba(0, 0, 0, 0.5), inset 0 1px 0 rgba(255, 255, 255, 0.07);
    --card-shadow: 0 2px 12px rgba(0, 0, 0, 0.18);
    --dialog-bg: rgba(15, 19, 40, 0.85);
    --noise-opacity: 0.35;
    --k-concept: #fbbf24;
    --k-edge: #34d399;
    --k-theme: #8b95f8;
    --k-supertheme: #e879f9;
    --k-superedge: #bccf5a;
    --k-tissue: #67e8f9;
    --k-story: #fb7185;
  }
}

/* ---- base ------------------------------------------------------------ */

* { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  background: var(--bg0);
  scrollbar-width: thin;
  scrollbar-color: var(--stroke-strong) transparent;
}

body {
  margin: 0;
  color: var(--fg);
  font-family: var(--serif);
  font-weight: 450;
  font-size: 1.15rem;
  line-height: 1.72;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

/* ambient aurora field */
body::before {
  content: "";
  position: fixed;
  inset: -25%;
  z-index: -2;
  pointer-events: none;
  background:
    radial-gradient(38% 45% at 18% 12%, rgba(99, 102, 241, 0.20), transparent 65%),
    radial-gradient(42% 48% at 85% 18%, rgba(8, 145, 178, 0.14), transparent 68%),
    radial-gradient(50% 55% at 72% 90%, rgba(192, 38, 211, 0.11), transparent 70%),
    radial-gradient(36% 42% at 6% 82%, rgba(56, 189, 248, 0.15), transparent 65%);
}
@media (prefers-color-scheme: dark) {
  body::before {
    background:
      radial-gradient(38% 45% at 18% 12%, rgba(109, 92, 255, 0.30), transparent 65%),
      radial-gradient(42% 48% at 85% 18%, rgba(45, 212, 191, 0.17), transparent 68%),
      radial-gradient(50% 55% at 72% 90%, rgba(232, 121, 249, 0.14), transparent 70%),
      radial-gradient(36% 42% at 6% 82%, rgba(56, 189, 248, 0.16), transparent 65%);
  }
}

/* film grain so the glass never bands */
body::after {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  opacity: calc(var(--noise-opacity) * 0.1);
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='2' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

@media (prefers-reduced-motion: no-preference) {
  body::before {
    animation: aurora-drift 90s ease-in-out infinite alternate;
  }
  @keyframes aurora-drift {
    from { transform: translate3d(-1.5%, -1%, 0) rotate(0deg) scale(1); }
    to   { transform: translate3d(1.5%, 2%, 0) rotate(3deg) scale(1.07); }
  }
  main { animation: rise 0.45s cubic-bezier(0.2, 0.7, 0.3, 1) both; }
  @keyframes rise {
    from { opacity: 0; transform: translateY(10px); }
  }
}

::selection { background: rgba(139, 149, 248, 0.35); }

:focus-visible {
  outline: 2px solid var(--acc-a);
  outline-offset: 2px;
  border-radius: 4px;
}

::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb {
  background: var(--stroke-strong);
  border-radius: 8px;
  border: 2px solid transparent;
  background-clip: content-box;
}

/* ---- frame: header / panel / footer ----------------------------------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background: var(--header-bg);
  -webkit-backdrop-filter: blur(18px) saturate(1.4);
  backdrop-filter: blur(18px) saturate(1.4);
  border-bottom: 1px solid var(--stroke);
}

.header-inner {
  width: min(1060px, 100% - 1.4rem);
  margin: 0 auto;
  padding: 0.62rem 0.15rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  font-family: var(--sans);
  font-size: 0.88rem;
}

.home-link {
  color: var(--muted);
  text-decoration: none;
  font-weight: 600;
  letter-spacing: 0.015em;
  display: inline-flex;
  align-items: baseline;
  gap: 0.5rem;
}
.home-link b {
  color: var(--fg);
  font-weight: 700;
  letter-spacing: -0.01em;
}
.home-sub {
  color: var(--faint);
  font-weight: 500;
  font-size: 0.82em;
}
.home-link:hover b { color: var(--acc-a); }
@media (max-width: 560px) { .home-sub { display: none; } }

.header-tools {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
}
.help-link {
  color: var(--muted);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.78rem;
  letter-spacing: 0.02em;
  padding: 0.2rem 0.66rem;
  border: 1px solid var(--stroke-strong);
  border-radius: 999px;
}
.help-link:hover { color: var(--acc-a); border-color: var(--acc-a); }
.help-link[aria-current="page"] { color: var(--fg); border-color: var(--stroke-strong); }

/* ---- help page ----------------------------------------------------------- */

.help-figure {
  margin: 1.15rem 0 1.5rem;
}
.help-figure img {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--stroke-strong);
  border-radius: 14px;
  box-shadow: var(--card-shadow);
}
.help-figure figcaption {
  font-family: var(--sans);
  font-size: 0.84rem;
  line-height: 1.5;
  color: var(--muted);
  margin-top: 0.55rem;
}
.help-kinds li { margin: 0.45rem 0; }

.page {
  width: min(1060px, 100% - 1.4rem);
  margin: 1.15rem auto 2.8rem;
  padding: clamp(1.5rem, 4vw, 2.6rem) clamp(1.15rem, 4.5vw, 2.6rem) clamp(1.5rem, 4vw, 2.3rem);
  background: var(--panel);
  -webkit-backdrop-filter: blur(22px) saturate(1.4);
  backdrop-filter: blur(22px) saturate(1.4);
  border: 1px solid var(--stroke);
  border-radius: 22px;
  box-shadow: var(--panel-shadow);
}

.site-footer {
  margin-top: 2.8rem;
  padding-top: 1.1rem;
  border-top: 1px solid var(--stroke);
  font-family: var(--sans);
  font-size: 0.84rem;
}
.site-footer a { color: var(--muted); text-decoration: none; }
.site-footer a:hover { color: var(--fg); }

/* ---- typography -------------------------------------------------------- */

h1, h2, h3 {
  font-family: var(--sans);
  line-height: 1.22;
  font-weight: 600;
}

h1 {
  font-size: clamp(1.5rem, 1.2rem + 1.4vw, 2rem);
  letter-spacing: -0.022em;
  margin: 0 0 0.8rem;
  text-wrap: balance;
}
main > h1:first-child::before {
  content: "";
  display: block;
  width: 44px;
  height: 3px;
  border-radius: 3px;
  background: linear-gradient(90deg, var(--acc-a), var(--acc-c));
  margin-bottom: 1rem;
}

.pk-index main > h1.hero-title {
  font-size: clamp(2.6rem, 1.5rem + 5vw, 4.4rem);
  font-weight: 680;
  letter-spacing: -0.03em;
  line-height: 1.02;
  margin-bottom: 0.15rem;
  background: var(--hero-grad);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.hero-tag {
  font-family: var(--sans);
  font-size: clamp(0.92rem, 0.85rem + 0.4vw, 1.08rem);
  font-weight: 500;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 0 1.4rem;
}

h2 {
  font-size: 0.74rem;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: var(--muted);
  margin: 1.7rem 0 0.6rem;
}

.prose-section h2 {
  font-size: 1.16rem;
  text-transform: none;
  letter-spacing: -0.012em;
  color: var(--fg);
  margin: 1.9rem 0 0.55rem;
}

h3.letter-head {
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--acc-b);
  margin: 1.3rem 0 0.35rem;
  border-bottom: 1px solid var(--stroke);
  padding-bottom: 0.2rem;
}

p { margin: 0 0 2rem; }

.lede {
  font-size: 1.22rem;
  line-height: 1.55;
  font-weight: 420;
  margin-bottom: 1.1rem;
}

/* gentle two-paragraph page introduction — plain prose, part of the page flow */
.page-intro { margin: 0 0 1.6rem; }

.origins, .edge-meta {
  font-family: var(--sans);
  font-size: 0.84rem;
  color: var(--muted);
  margin-bottom: 1.2rem;
}

blockquote {
  margin: 1.1rem 0;
  padding: 0.15rem 0 0.15rem 1rem;
  border-left: 2px solid;
  border-image: linear-gradient(180deg, var(--acc-a), var(--acc-c)) 1;
  color: var(--muted);
  font-style: italic;
}

code {
  font-family: var(--mono);
  font-size: 0.88em;
  background: var(--chip);
  border: 1px solid var(--stroke);
  border-radius: 6px;
  padding: 0.06em 0.35em;
}

/* ---- links ------------------------------------------------------------- */

a {
  color: var(--link);
  text-decoration: underline;
  text-decoration-color: transparent;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
  transition: text-decoration-color 0.15s ease, color 0.15s ease;
}
a:hover { text-decoration-color: currentColor; }
a:visited { color: var(--link-visited); }

a.cite {
  color: var(--muted);
  font-size: 0.92em;
  text-decoration-style: dotted;
  text-decoration-color: var(--stroke-strong);
}
a.cite:hover { color: var(--fg); text-decoration-color: currentColor; }

.linklike {
  background: none;
  border: none;
  padding: 0;
  font: inherit;
  color: var(--link);
  cursor: pointer;
}
.linklike:hover { text-decoration: underline; }

/* ---- chips, badges, tags ------------------------------------------------ */

.kind-concept    { --k: var(--k-concept); }
.kind-edge       { --k: var(--k-edge); }
.kind-theme      { --k: var(--k-theme); }
.kind-supertheme { --k: var(--k-supertheme); }
.kind-superedge  { --k: var(--k-superedge); }
.kind-tissue     { --k: var(--k-tissue); }
.kind-story      { --k: var(--k-story); }
.role-introduced { --k: var(--k-concept); }
.role-refined    { --k: var(--k-theme); }
.role-inherited  { --k: var(--muted); }

.kind-badge {
  display: inline-block;
  font-family: var(--sans);
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding: 0.22rem 0.62rem;
  border-radius: 999px;
  color: var(--k, var(--muted));
  border: 1px solid color-mix(in srgb, var(--k, var(--muted)) 40%, transparent);
  background: color-mix(in srgb, var(--k, var(--muted)) 10%, transparent);
  white-space: nowrap;
}

.tag {
  display: inline-block;
  font-family: var(--sans);
  font-size: 0.66rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 0.1rem 0.45rem;
  border-radius: 999px;
  vertical-align: middle;
}
.tag.hindsight {
  color: var(--k-concept);
  border: 1px solid color-mix(in srgb, var(--k-concept) 45%, transparent);
  background: color-mix(in srgb, var(--k-concept) 10%, transparent);
}

.role { font-weight: 600; color: var(--k, var(--muted)); }

.era-tag {
  display: inline-block;
  font-family: var(--sans);
  font-size: 0.66rem;
  font-weight: 500;
  border: 1px solid var(--stroke);
  background: var(--chip);
  border-radius: 999px;
  padding: 0.08rem 0.5rem;
  color: var(--muted);
  margin-left: 0.45rem;
  vertical-align: middle;
  white-space: nowrap;
}

.muted { color: var(--muted); font-size: 0.85em; }

/* ---- content blocks ------------------------------------------------------ */

.prose-section { margin-bottom: 1.5rem; }

.divider {
  border: none;
  height: 1px;
  margin: 2.2rem 0 1.4rem;
  background: linear-gradient(90deg, transparent, var(--stroke-strong), transparent);
}

.nav-block {
  margin: 0 0 0.9rem;
  padding: 1.05rem 1.3rem 1.1rem;
  background: var(--card);
  border: 1px solid var(--stroke);
  border-radius: 16px;
  box-shadow: var(--card-shadow);
}
.nav-block > h2 {
  margin: 0 0 0.55rem;
  display: flex;
  align-items: center;
  gap: 0.55rem;
}
.nav-block > h2::before {
  content: "";
  width: 14px;
  height: 2px;
  border-radius: 2px;
  background: linear-gradient(90deg, var(--acc-a), var(--acc-c));
}
.nav-block ul { padding-left: 1.2rem; margin: 0.3rem 0; }
.nav-block li { margin: 0.3rem 0; }

.connections { list-style: none; padding-left: 0; }
.nav-block ul.connections { padding-left: 0; }
.connections li {
  padding: 0.38rem 0.1rem;
  border-bottom: 1px solid var(--stroke);
}
.connections li:last-child { border-bottom: none; }

.section-note {
  font-family: var(--sans);
  font-size: 0.85rem;
  color: var(--muted);
}

/* sources */
.sources {
  list-style: none;
  padding-left: 0;
  font-family: var(--sans);
  font-size: 0.85rem;
  margin: 0.3rem 0;
}
.nav-block ul.sources { padding-left: 0; }
.source-paper { margin: 0.5rem 0; }
.source-locs {
  padding-left: 1.2rem;
  margin: 0.2rem 0;
  color: var(--muted);
}
.source-locs li { margin: 0.18rem 0; }

.sources-details > summary {
  cursor: pointer;
  font-family: var(--sans);
  font-size: 0.85rem;
  color: var(--muted);
}
.sources-details > summary:hover { color: var(--fg); }
.sources-details[open] > summary { margin-bottom: 0.3rem; }

.supertheme-list { list-style: none; padding-left: 0; }
.supertheme-list > li { margin-bottom: 0.95rem; }
.theme-sublist { padding-left: 1.3rem; margin-top: 0.3rem; }

.concept-az {
  columns: 2;
  column-gap: 2.2rem;
  padding-left: 1.1rem;
  list-style: disc;
}
.concept-az li::marker { color: var(--faint); }

/* ---- index tabs ----------------------------------------------------------- */

.tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  padding: 5px;
  width: fit-content;
  max-width: 100%;
  background: var(--chip);
  border: 1px solid var(--stroke);
  border-radius: 16px;
  box-shadow: var(--card-shadow);
  margin: 1.5rem 0 1.4rem;
  font-family: var(--sans);
}
.tab {
  background: none;
  border: none;
  border-radius: 11px;
  padding: 0.48rem 0.9rem;
  font-family: var(--sans);
  font-size: 0.87rem;
  font-weight: 500;
  color: var(--muted);
  cursor: pointer;
  transition: color 0.15s ease, background 0.15s ease;
}
.tab:hover { color: var(--fg); background: var(--hover); }
.tab.active {
  color: var(--fg);
  font-weight: 600;
  background: var(--panel);
  box-shadow: inset 0 0 0 1px var(--stroke-strong), 0 2px 8px rgba(0, 0, 0, 0.12);
}
.panel-title { display: none; }

/* ---- story sub-tabs (lenses over the same corpus) ---------------------- */

.subtabs {
  display: flex;
  flex-wrap: wrap;
  gap: 3px;
  margin: 0.4rem 0 1.3rem;
  padding-bottom: 0.55rem;
  border-bottom: 1px solid var(--stroke);
  font-family: var(--sans);
}
.subtab {
  background: none;
  border: 1px solid transparent;
  border-radius: 10px;
  padding: 0.38rem 0.8rem;
  font-family: var(--sans);
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--muted);
  cursor: pointer;
  transition: color 0.15s ease, background 0.15s ease, border-color 0.15s ease;
}
.subtab:hover { color: var(--fg); background: var(--hover); }
.subtab.active {
  color: var(--fg);
  font-weight: 600;
  background: var(--chip);
  border-color: var(--stroke-strong);
}
.story-panel[hidden] { display: none; }

/* ---- overlay story tree ------------------------------------------------ */

.tree-controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.4rem;
  margin: 0.9rem 0 1.2rem;
  font-family: var(--sans);
}
.controls-label {
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.13em;
  color: var(--faint);
  margin-right: 0.25rem;
}
.gran-chip {
  font-family: var(--sans);
  font-size: 0.78rem;
  font-weight: 500;
  color: var(--muted);
  background: var(--chip);
  border: 1px solid var(--stroke);
  border-radius: 999px;
  padding: 0.3rem 0.75rem;
  cursor: pointer;
  transition: color 0.15s ease, border-color 0.15s ease, background 0.15s ease;
}
.gran-chip:hover {
  color: var(--fg);
  border-color: var(--stroke-strong);
  background: var(--hover);
}

.tree-node > summary {
  cursor: pointer;
  list-style: none;
  padding: 0.3rem 0.45rem;
  margin-inline: -0.45rem;
  border-radius: 9px;
  line-height: 1.5;
  transition: background 0.15s ease;
}
.tree-node > summary:hover { background: var(--hover); }
.tree-node > summary::-webkit-details-marker { display: none; }
.tree-node > summary::before {
  content: "+";
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1.25rem;
  height: 1.25rem;
  margin-right: 0.55rem;
  border-radius: 7px;
  background: var(--chip);
  border: 1px solid var(--stroke);
  color: var(--acc-a);
  font-family: var(--sans);
  font-size: 0.85rem;
  font-weight: 600;
  vertical-align: -0.22em;
  transition: border-color 0.15s ease;
}
.tree-node > summary:hover::before {
  border-color: color-mix(in srgb, var(--acc-a) 55%, transparent);
}
.tree-node[open] > summary::before { content: "−"; }

.node-body {
  margin: 0.15rem 0 0.8rem 0.6rem;
  padding-left: 1.05rem;
  border-left: 1px solid var(--stroke-strong);
}

.node-root > summary {
  font-family: var(--sans);
  font-size: 1.13rem;
  font-weight: 650;
  line-height: 1.35;
}
.node-arc > summary { font-family: var(--sans); font-size: 1rem; font-weight: 650; }
.node-supertheme > summary { font-family: var(--sans); font-weight: 600; }
.node-theme > summary { font-family: var(--sans); font-size: 0.95rem; }
.node-superedges > summary { font-family: var(--sans); font-size: 0.88rem; color: var(--muted); }
.node-rolegroup > summary { font-family: var(--sans); font-size: 0.95rem; font-weight: 600; }

/* ---- papers tab cards --------------------------------------------------- */

.paper-cards {
  display: grid;
  gap: 0.9rem;
  margin: 0.4rem 0 1.3rem;
}
.paper-card {
  padding: 0.95rem 1.15rem 1rem;
  background: var(--card);
  border: 1px solid var(--stroke);
  border-radius: 16px;
  box-shadow: var(--card-shadow);
}
.paper-card .pc-title {
  margin: 0 0 0.25rem;
  font-family: var(--sans);
  font-size: 1.05rem;
  font-weight: 650;
  line-height: 1.35;
}
.paper-card .pc-title a { color: var(--fg); text-decoration: none; }
.paper-card .pc-title a:hover { color: var(--link); }
.paper-card .edge-meta { margin: 0; }

.arc-num {
  color: var(--acc-a);
  margin-right: 0.55rem;
  font-size: 0.7rem;
  font-weight: 650;
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

.node-narrative p { margin: 0.4rem 0 0.85rem; }

.tree-count {
  font-family: var(--sans);
  font-size: 0.76em;
  font-weight: 400;
  color: var(--faint);
  font-variant-numeric: tabular-nums;
}
.tree-kind {
  font-family: var(--sans);
  font-size: 0.62rem;
  font-weight: 650;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-left: 0.4rem;
  color: var(--k, var(--muted));
}

.tree-concepts {
  list-style: none;
  padding-left: 0;
  margin: 0.3rem 0;
}
.tree-concepts > li { margin: 0.15rem 0; }
.tree-leaf { padding-left: 1.85rem; }

.tree-edges {
  list-style: none;
  padding-left: 1.85rem;
  margin: 0.2rem 0 0.55rem;
  font-size: 0.93rem;
}
.tree-edges li { margin: 0.26rem 0; }

.walk-step { margin-bottom: 0.35rem; }
.walk-prose {
  margin: 0.05rem 0 0.75rem 1.85rem;
  font-size: 0.96rem;
}
.walk-prose p { margin: 0 0 0.45rem; }

ol.walk { padding-left: 1.5rem; }
ol.walk > li { margin: 0.6rem 0; }
ol.walk > li::marker {
  font-family: var(--sans);
  font-size: 0.85em;
  font-weight: 600;
  color: var(--acc-b);
}
ol.walk .walk-prose { margin-left: 0; }

/* ---- popup dialog --------------------------------------------------------- */

.popup-dialog {
  padding: 0;
  border: 1px solid var(--stroke-strong);
  border-radius: 18px;
  background: var(--dialog-bg);
  -webkit-backdrop-filter: blur(28px) saturate(1.4);
  backdrop-filter: blur(28px) saturate(1.4);
  color: var(--fg);
  width: min(86ch, 94vw);
  height: min(85vh, 60rem);
  max-width: 94vw;
  max-height: 85vh;
  box-shadow: 0 32px 90px rgba(0, 0, 0, 0.5);
  overflow: hidden;
}
.popup-dialog[open] {
  display: flex;
  flex-direction: column;
}
.popup-dialog::backdrop {
  background: rgba(5, 7, 16, 0.45);
  -webkit-backdrop-filter: blur(6px);
  backdrop-filter: blur(6px);
}

.popup-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.45rem 0.55rem 0.45rem 1rem;
  border-bottom: 1px solid var(--stroke);
  font-family: var(--sans);
  font-size: 0.82rem;
  flex: none;
}
.popup-full { color: var(--muted); text-decoration: none; }
.popup-full:hover { color: var(--fg); }
.popup-close {
  background: none;
  border: none;
  padding: 0 0.55rem;
  font-family: var(--sans);
  font-size: 1.35rem;
  line-height: 1;
  color: var(--muted);
  cursor: pointer;
  border-radius: 8px;
}
.popup-close:hover { color: var(--fg); background: var(--hover); }

.popup-frame {
  border: none;
  width: 100%;
  flex: 1;
  background: var(--bg0);
}

/* page rendered inside a popup frame: hide the site chrome */
.in-popup .site-header,
.in-popup .site-footer { display: none; }
.in-popup .page {
  margin: 0.9rem auto 1.4rem;
  width: min(1060px, 100% - 1.1rem);
}

/* ---- math / misc ------------------------------------------------------- */

.katex-display { overflow-x: auto; overflow-y: hidden; padding: 0.2rem 0; }

/* ---- responsive -------------------------------------------------------- */

@media (max-width: 640px) {
  body { font-size: 1.08rem; }
  .concept-az { columns: 1; }
  .page { border-radius: 16px; margin-top: 0.8rem; }
  .node-body { margin-left: 0.45rem; padding-left: 0.75rem; }
  .tree-leaf, .walk-prose { padding-left: 1.4rem; }
  .walk-prose { margin-left: 1.4rem; padding-left: 0; }
  .tree-edges { padding-left: 1.4rem; }
}