/* Design system for the interactive project pages ("explorables"). Dark by design. */

:root {
  color-scheme: dark;
  --bg: #0b0e14;
  --surface: #131922;
  --surface-2: #1a2230;
  --line: #263041;
  --line-2: #344056;
  --ink: #e8ebf0;
  --ink-2: #b9c1cd;
  --muted: #8b94a3;
  --link: #8cc4ff;
  --accent: #3987e5;
  --metro: #3987e5;
  --wolff: #d95926;
  --aqua: #199e70;
  --good: #0ca30c;
  --warn: #fab219;
  --bad: #ec835a;
  --serif: "Source Serif 4", Charter, Georgia, serif;
  --sans: "Inter", system-ui, -apple-system, "Segoe UI", sans-serif;
  --mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
  --measure: 720px;
  --wide: 1040px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 72px; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}

body.xp {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 18px/1.7 var(--serif);
  -webkit-font-smoothing: antialiased;
}

.xp a { color: var(--link); text-decoration-thickness: 1px; text-underline-offset: 3px; }
.xp a:hover { color: #b8dbff; }

.xp-skip { position: absolute; left: -9999px; }
.xp-skip:focus { left: 16px; top: 12px; z-index: 10; background: var(--surface); padding: 8px 12px; border-radius: 8px; }

/* ---- top bar */
.xp-bar {
  position: sticky; top: 0; z-index: 5;
  display: flex; align-items: center; justify-content: space-between; gap: 16px;
  padding: 14px clamp(16px, 4vw, 40px);
  font-family: var(--sans); font-size: 15px;
  background: rgba(11, 14, 20, 0.82);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
.xp-bar .xp-brand { color: var(--ink); font-weight: 700; text-decoration: none; letter-spacing: 0.01em; }
.xp-bar nav { display: flex; gap: clamp(12px, 2.5vw, 28px); flex-wrap: wrap; }
.xp-bar nav a { color: var(--ink-2); text-decoration: none; }
.xp-bar nav a:hover { color: var(--ink); }

/* ---- hero */
.xp-hero {
  position: relative;
  display: grid; grid-template-columns: 1fr; gap: 24px;
  max-width: 1240px; margin: 0 auto;
  padding: clamp(32px, 6vw, 72px) clamp(16px, 4vw, 40px) 24px;
}
@media (min-width: 900px) {
  .xp-hero { grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr); align-items: center; }
}
.xp-hero--text { max-width: 1160px; }
@media (min-width: 900px) {
  .xp-hero.xp-hero--text { grid-template-columns: minmax(0, 1fr); }
  .xp-hero--text .xp-facts { max-width: none; grid-template-columns: repeat(4, minmax(0, 1fr)); }
}
.xp-kicker { margin: 0 0 12px; font: 600 13px/1.4 var(--mono); letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); }
.xp-hero h1 { margin: 0; font: 700 clamp(36px, 6vw, 64px)/1.04 var(--sans); letter-spacing: -0.025em; }
.xp-sub { margin: 18px 0 0; font-size: clamp(18px, 2vw, 21px); line-height: 1.55; color: var(--ink-2); max-width: 36em; }
.xp-facts { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; margin: 28px 0 0; max-width: 540px; }
.xp-facts div { background: var(--surface); border: 1px solid var(--line); border-radius: 12px; padding: 10px 14px; }
.xp-facts dt { font: 500 12px/1.4 var(--sans); color: var(--muted); }
.xp-facts dd { margin: 2px 0 0; font: 600 18px/1.3 var(--serif); font-variant-numeric: tabular-nums; color: var(--ink); }
.xp-hero-fig { margin: 0; }
.xp-hero-fig canvas { display: block; width: 100%; aspect-ratio: 1; cursor: grab; touch-action: none; }
.xp-hero-fig canvas:active { cursor: grabbing; }
.xp-hero-fig figcaption { font: 13px/1.5 var(--sans); color: var(--muted); text-align: center; }

/* ---- body: section nav + article */
.xp-body { max-width: 1240px; margin: 0 auto; padding: 0 clamp(16px, 4vw, 40px); display: grid; grid-template-columns: 1fr; }
@media (min-width: 1180px) {
  .xp-body { grid-template-columns: 200px minmax(0, 1fr); gap: 48px; }
  .xp-toc {
    position: sticky; top: 84px; align-self: start;
    display: flex; flex-direction: column; gap: 2px;
    max-height: calc(100vh - 110px); overflow-y: auto;
    font: 13px/1.35 var(--sans); padding-top: 40px;
  }
  .xp-toc a { color: var(--muted); text-decoration: none; padding: 5px 0 5px 12px; border-left: 2px solid var(--line); }
  .xp-toc a:hover { color: var(--ink-2); }
  .xp-toc a.on { color: var(--ink); border-left-color: var(--accent); }
}
@media (max-width: 1179px) { .xp-toc { display: none; } }

.xp-article { min-width: 0; padding-bottom: 80px; }
.xp-article > * { max-width: var(--measure); }
.xp-article > .wide, .xp-article > .xp-widget, .xp-article > .xp-grid2 { max-width: var(--wide); }

.xp-article h2 {
  font: 700 clamp(26px, 3.4vw, 34px)/1.15 var(--sans); letter-spacing: -0.015em;
  margin: 88px 0 18px; padding-top: 20px; border-top: 1px solid var(--line);
}
.xp-article h2 .num { display: block; font: 500 13px/1.4 var(--mono); color: var(--muted); letter-spacing: 0.08em; margin-bottom: 10px; }
.xp-article h3 { font: 600 20px/1.3 var(--sans); margin: 40px 0 10px; }
.xp-article p, .xp-article li { color: var(--ink-2); }
.xp-article strong { color: var(--ink); font-weight: 600; }
.xp-article em { color: var(--ink); }
.xp-article .lead { font-size: 21px; line-height: 1.6; color: var(--ink); }

.xp-article ul, .xp-article ol { padding-left: 1.3em; }
.xp-article li { margin: 0.3em 0; }

.xp-article .katex { font-size: 1.05em; color: var(--ink); }
.xp-article .katex-display { overflow-x: auto; overflow-y: hidden; padding: 6px 0; margin: 1.2em 0; }

.xp-article code { font: 0.85em var(--mono); background: var(--surface-2); padding: 2px 6px; border-radius: 6px; }

/* callouts */
.note, .aside {
  background: var(--surface); border: 1px solid var(--line); border-left: 3px solid var(--accent);
  border-radius: 10px; padding: 14px 18px; margin: 24px 0; font-size: 16.5px;
}
.aside { border-left-color: var(--line-2); }
.note p, .aside p { margin: 0.4em 0; }
.note .label, .aside .label { display: block; font: 600 12px/1.4 var(--mono); letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); margin-bottom: 4px; }

/* tables */
.xp-article table { width: 100%; border-collapse: collapse; font: 15px/1.45 var(--sans); margin: 20px 0; }
.xp-article th, .xp-article td { padding: 9px 10px; border-bottom: 1px solid var(--line); text-align: left; color: var(--ink-2); }
.xp-article th { color: var(--muted); font-weight: 600; font-size: 13px; }
.xp-article td.num, .xp-article th.num { text-align: right; font-family: var(--mono); font-variant-numeric: tabular-nums; }
.xp-article tr.hl td { color: var(--ink); background: rgba(57, 135, 229, 0.08); }
.table-scroll { overflow-x: auto; }

/* timeline */
.timeline { list-style: none; padding: 0; margin: 24px 0; border-left: 1px solid var(--line-2); }
.timeline li { position: relative; padding: 0 0 18px 26px; margin: 0; }
.timeline li::before { content: ""; position: absolute; left: -5px; top: 9px; width: 9px; height: 9px; border-radius: 50%; background: var(--accent); box-shadow: 0 0 0 3px var(--bg); }
.timeline .yr { font: 500 14px var(--mono); color: var(--ink); margin-right: 8px; }

/* cards (applications etc.) */
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(210px, 1fr)); gap: 12px; margin: 24px 0; max-width: var(--wide) !important; }
.card { background: var(--surface); border: 1px solid var(--line); border-radius: 12px; padding: 14px 16px; font-size: 15.5px; line-height: 1.55; }
.card b { display: block; font: 600 15px/1.35 var(--sans); color: var(--ink); margin-bottom: 4px; }
.card span { color: var(--ink-2); }

/* ---- interactive widgets */
.xp-widget {
  background: var(--surface); border: 1px solid var(--line); border-radius: 16px;
  padding: clamp(14px, 2.4vw, 22px); margin: 32px 0;
  font-family: var(--sans); font-size: 15px; line-height: 1.5;
}
.xp-widget-head { display: flex; align-items: baseline; gap: 12px; flex-wrap: wrap; margin-bottom: 14px; }
.xp-widget-head h3 { margin: 0; font: 600 18px/1.3 var(--sans); color: var(--ink); }
.xp-tag { font: 600 11px/1 var(--mono); letter-spacing: 0.1em; text-transform: uppercase; color: #0b0e14; background: var(--ink-2); padding: 5px 7px; border-radius: 6px; }
.xp-tag.data { background: var(--aqua); color: #fff; }

.xp-stage { display: grid; grid-template-columns: 1fr; gap: 18px; }
@media (min-width: 760px) { .xp-stage { grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr); align-items: start; } }
.xp-stage.even { }
@media (min-width: 760px) { .xp-stage.even { grid-template-columns: 1fr 1fr; } }

.xp-panel { display: flex; flex-direction: column; gap: 8px; min-width: 0; }
.xp-panel-title { font: 600 13px/1.4 var(--mono); color: var(--ink-2); letter-spacing: 0.04em; }

canvas.xp-lattice, canvas.xp-ising, canvas.xp-slice, canvas.xp-metro, canvas.xp-wolff {
  display: block; width: 100%; aspect-ratio: 1; border-radius: 10px; background: #1d2635; image-rendering: pixelated;
}
canvas.xp-raster { display: block; width: 100%; margin-top: 8px; }
canvas.xp-cube { display: block; width: 100%; aspect-ratio: 1; border-radius: 10px; background: radial-gradient(circle at 50% 45%, #18202c, #0f141c 70%); cursor: grab; touch-action: none; }
canvas.xp-cube:active { cursor: grabbing; }
canvas.xp-trace { display: block; width: 100%; height: 90px; background: var(--bg); border: 1px solid var(--line); border-radius: 8px; }

.xp-controls { display: flex; flex-direction: column; gap: 14px; }
.xp-row { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }

.xp-slider { display: flex; flex-direction: column; gap: 6px; }
.xp-slider > span { display: flex; justify-content: space-between; gap: 12px; color: var(--ink-2); }
.xp-slider output { font: 500 14px var(--mono); color: var(--ink); }
.xp-slider input[type="range"] { width: 100%; accent-color: var(--accent); height: 28px; }

.xp-btn, .xp-seg button {
  font: 500 14px/1 var(--sans); color: var(--ink); background: var(--surface-2);
  border: 1px solid var(--line-2); border-radius: 999px; padding: 9px 14px; cursor: pointer;
}
.xp-btn:hover, .xp-seg button:hover { border-color: var(--muted); }
.xp-btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.xp-btn:focus-visible, .xp-seg button:focus-visible, .xp-slider input:focus-visible { outline: 2px solid var(--link); outline-offset: 2px; }
.xp-seg { display: inline-flex; border: 1px solid var(--line-2); border-radius: 999px; padding: 3px; background: var(--bg); }
.xp-seg button { border: 0; background: transparent; color: var(--ink-2); padding: 7px 13px; }
.xp-seg button[aria-pressed="true"] { background: var(--surface-2); color: var(--ink); box-shadow: inset 0 0 0 1px var(--line-2); }

.xp-readout { display: grid; grid-template-columns: repeat(auto-fit, minmax(110px, 1fr)); gap: 8px; }
.xp-readout div { background: var(--bg); border: 1px solid var(--line); border-radius: 10px; padding: 8px 10px; }
.xp-readout dt, .xp-readout .k { font-size: 12px; color: var(--muted); }
.xp-readout dd, .xp-readout .v { margin: 0; font: 500 16px/1.3 var(--mono); color: var(--ink); }
.xp-readout [data-q="good"] { color: var(--good); }
.xp-readout [data-q="mid"] { color: var(--warn); }
.xp-readout [data-q="bad"] { color: var(--bad); }

.xp-key { display: flex; flex-wrap: wrap; gap: 14px; font-size: 13px; color: var(--ink-2); }
.xp-key i { display: inline-block; width: 12px; height: 12px; border-radius: 3px; margin-right: 6px; vertical-align: -1px; background: var(--c); }
.xp-key i.ring { background: transparent; box-shadow: inset 0 0 0 2px #fff; }
.xp-key .spin-wheel { width: 44px; height: 14px; border-radius: 7px; background: linear-gradient(90deg, #d4776b, #b78a39, #6f9c4c, #2fa18f, #3a95c4, #8a7fd1, #c26fae, #d4776b); }

.xp-caption { margin: 14px 0 0; font-size: 14px; line-height: 1.55; color: var(--muted); }

.xp-grid2 { display: grid; grid-template-columns: 1fr; gap: 16px; margin: 28px 0; }
@media (min-width: 860px) { .xp-grid2 { grid-template-columns: 1fr 1fr; } }
.xp-grid2 .xp-widget { margin: 0; }

/* ---- charts */
.xp-chart { font-family: var(--sans); }
.xp-chart-wrap { position: relative; }
.xp-chart svg { display: block; width: 100%; height: auto; overflow: visible; }
.xp-legend { display: flex; flex-wrap: wrap; gap: 6px 16px; margin: 0 0 8px; font-size: 13px; color: var(--ink-2); min-height: 4px; }
.xp-legend-item i { display: inline-block; vertical-align: middle; margin-right: 6px; }
.xp-legend-item i.dot { width: 9px; height: 9px; border-radius: 50%; background: var(--c); }
.xp-legend-item i.line { width: 18px; height: 0; border-top: 2px solid var(--c); }
.xp-legend-item i.line.dash { border-top-style: dashed; }
.xp-grid { stroke: #222b3a; stroke-width: 1; }
.xp-base { stroke: #344056; stroke-width: 1; }
.xp-tick { fill: var(--muted); font: 12px var(--sans); font-variant-numeric: tabular-nums; }
.xp-label { fill: var(--ink-2); font: 13px var(--sans); }
.xp-line, .xp-curve { fill: none; stroke-width: 2; stroke-linejoin: round; stroke-linecap: round; }
.xp-dash { stroke-dasharray: 6 5; }
.xp-err { stroke-width: 1.2; }
.xp-dot { stroke: var(--surface); stroke-width: 2; }
.xp-hl { fill: none; stroke-width: 2; pointer-events: none; }
.xp-ref { stroke: var(--ink-2); stroke-width: 1; stroke-dasharray: 4 4; }
.xp-band { fill: rgba(185, 193, 205, 0.08); }
.xp-reflabel, .xp-note { fill: var(--ink-2); font: 12px var(--sans); }
.xp-tip {
  position: absolute; pointer-events: none; opacity: 0; transition: opacity 0.1s;
  background: #0b0e14; border: 1px solid var(--line-2); border-radius: 8px; padding: 7px 9px;
  font: 12.5px/1.45 var(--sans); color: var(--ink-2); white-space: nowrap; z-index: 2;
}
.xp-tip b { color: var(--ink); font-weight: 600; }
.xp-table { margin-top: 8px; font-size: 13px; color: var(--muted); }
.xp-table summary { cursor: pointer; }
.xp-table-scroll { max-height: 260px; overflow: auto; }
.xp-table table { font-size: 12.5px !important; }

/* ---- results table and references */
.refs { font-size: 15px; }
.refs li { margin: 0.5em 0; }

.xp-footer { border-top: 1px solid var(--line); padding: 28px clamp(16px, 4vw, 40px); font: 14px var(--sans); color: var(--muted); text-align: center; }
.xp-footer a { color: var(--ink-2); }

@media (max-width: 600px) {
  body.xp { font-size: 17px; }
  .xp-article h2 { margin-top: 64px; }
}

[hidden] { display: none !important; }

.gr, .xp-chart tspan.gr { font-family: var(--serif); font-style: italic; }