:root {
  color-scheme: dark;
  --ground: #12100E;   /* warm near-black — the canvas field */
  --panel:  #17140F;   /* warm graphite — opaque; panels sit beside the habitat, not over it */
  --divider:#332E29;   /* hairline */
  --ink:    #D6CFC6;   /* bone text */
  --muted:  #8A8078;
  --accent: #C9873A;   /* muted amber — active controls & hover only */
  --mono: "SF Mono", "JetBrains Mono", "DejaVu Sans Mono", ui-monospace, monospace;
  --sans: "Inter", "Helvetica Neue", system-ui, sans-serif;
  --side: 500px;
  --bottom: 176px;
}

* { box-sizing: border-box; }
html, body { height: 100%; margin: 0; background: var(--ground); color: var(--ink); font-family: var(--mono); font-size: 22px; overflow: hidden; }

/* The habitat occupies its own region — the top-left rectangle left of the side
   panel and above the bottom bar — so the fixed UI never covers live particles. */
#stage { position: fixed; top: 0; left: 0; right: var(--side); bottom: var(--bottom); overflow: hidden; }
#canvas { display: block; width: 100%; height: 100%; touch-action: none; }  /* drags paint, not scroll */

#side {
  position: fixed; top: 0; right: 0; height: 100vh; width: var(--side); z-index: 3;
  border-left: 1px solid var(--divider); background: var(--panel);
  overflow-y: auto; overflow-x: hidden;
}
#bottom {
  position: fixed; left: 0; bottom: 0; width: calc(100vw - var(--side)); height: var(--bottom); z-index: 3;
  border-top: 1px solid var(--divider); background: var(--panel);
  display: flex; gap: 1px;
}

/* sparklines */
.spark { flex: 1 1 0; padding: 10px 13px; border-right: 1px solid var(--divider); min-width: 0; display: flex; flex-direction: column; }
.spark:last-child { border-right: none; }
.spark .lbl { color: var(--muted); text-transform: uppercase; letter-spacing: 0.06em; font-size: 12px; display: flex; flex-direction: column; align-items: flex-start; gap: 1px; min-width: 0; }
.spark .lbl > span:first-child { white-space: nowrap; overflow: hidden; text-overflow: ellipsis; max-width: 100%; }
.spark .val { color: var(--ink); font-size: 18px; }
.spark.headline .val { color: var(--accent); }
.spark canvas { width: 100%; flex: 1 1 0; margin-top: 6px; }
.spark select { background: transparent; color: var(--muted); border: none; font-family: var(--mono); font-size: 12px; text-transform: uppercase; letter-spacing: 0.06em; padding: 0; max-width: 100%; }

/* side panel */
section { border-bottom: 1px solid var(--divider); padding: 16px 18px; }
section > h2 { font-family: var(--sans); font-weight: 600; font-size: 18px; letter-spacing: 0.14em; text-transform: uppercase; color: var(--muted); margin: 0 0 12px; display: flex; align-items: baseline; gap: 8px; }
.scope { font-family: var(--mono); font-weight: 500; font-size: 12px; letter-spacing: 0.04em; text-transform: none; padding: 2px 7px; border-radius: 10px; border: 1px solid var(--divider); cursor: help; }
.scope.live { color: var(--accent); border-color: rgba(201,135,58,0.5); }
.scope.neu { color: #7FA6B8; border-color: rgba(127,166,184,0.45); }
.scope.reset { color: var(--muted); }
.scope.view { color: var(--muted); }
.row { display: flex; align-items: center; gap: 10px; margin: 8px 0; }
.row.wrap { flex-wrap: wrap; }

.ctrl { display: grid; grid-template-columns: 128px 1fr 72px; align-items: center; gap: 12px; margin: 7px 0; }
.ctrl label { color: var(--muted); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.ctrl output { text-align: right; color: var(--ink); }
.ctrl.stack { grid-template-columns: 1fr 72px; row-gap: 2px; }
.ctrl.stack label { grid-column: 1 / -1; overflow: visible; white-space: normal; }

input[type=range] { -webkit-appearance: none; appearance: none; height: 5px; background: var(--divider); border-radius: 3px; outline: none; }
input[type=range]::-webkit-slider-thumb { -webkit-appearance: none; width: 18px; height: 18px; border-radius: 50%; background: var(--ink); cursor: pointer; border: none; }
input[type=range]::-moz-range-thumb { width: 18px; height: 18px; border-radius: 50%; background: var(--ink); cursor: pointer; border: none; }
input[type=range]:focus-visible::-webkit-slider-thumb { box-shadow: 0 0 0 3px var(--accent); }

button, select, input[type=number], input[type=text] {
  font-family: var(--mono); font-size: 20px; color: var(--ink);
  background: rgba(18,16,14,0.6); border: 1px solid var(--divider); border-radius: 4px; padding: 7px 11px; cursor: pointer;
}
button:hover, select:hover { border-color: var(--accent); }
button.on { border-color: var(--accent); color: var(--accent); }
button:focus-visible, select:focus-visible, input:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
input[type=number], input[type=text] { cursor: text; width: 100%; }
.grid2 { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.grid5 { display: grid; grid-template-columns: repeat(5, 1fr); gap: 6px; }
.grid7 { display: grid; grid-template-columns: repeat(7, 1fr); gap: 5px; }
.grid7 button { padding: 7px 0; text-align: center; }
[data-tip] { cursor: help; }
[data-tip] input, [data-tip] select, [data-tip] button { cursor: pointer; }
.seg { display: flex; gap: 0; }
.seg button { border-radius: 0; flex: 1; border-right: none; }
.seg button:first-child { border-radius: 4px 0 0 4px; }
.seg button:last-child { border-radius: 0 4px 4px 0; border-right: 1px solid var(--divider); }
.hint { color: var(--muted); font-size: 17px; line-height: 1.5; margin: 8px 0 0; }

#tooltip {
  position: absolute; pointer-events: none; z-index: 5; display: none;
  background: rgba(18,16,14,0.95); border: 1px solid var(--divider); border-radius: 5px;
  padding: 12px 15px; font-size: 18px; line-height: 1.5; max-width: 340px; color: var(--ink);
}
#tooltip .k { color: var(--muted); }
#tooltip b { color: var(--accent); font-weight: 600; }

#uitip {
  position: fixed; z-index: 20; pointer-events: none; display: none;
  max-width: 420px; padding: 11px 14px; font-size: 16px; line-height: 1.45; white-space: pre-line;
  color: var(--ink); background: rgba(20, 18, 15, 0.97); border: 1px solid var(--divider);
  border-radius: 6px; box-shadow: 0 6px 22px rgba(0,0,0,0.5);
}

#hud { position: absolute; top: 16px; left: 18px; right: 120px; z-index: 4; color: var(--muted); font-size: 18px; letter-spacing: 0.06em; pointer-events: none; text-shadow: 0 1px 3px rgba(0,0,0,0.6); }
#hud b { color: var(--ink); }
kbd { color: var(--ink); background: var(--panel); border: 1px solid var(--divider); border-radius: 4px; padding: 0 6px; }

#starthint {
  position: absolute; left: 50%; top: 50%; transform: translate(-50%, -50%); z-index: 4; display: none; pointer-events: none;
  padding: 12px 22px; border: 1px solid var(--divider); border-radius: 999px; background: rgba(18,16,14,0.88);
  color: var(--muted); font-size: 18px; white-space: nowrap; box-shadow: 0 6px 22px rgba(0,0,0,0.5);
}
#starthint b { color: var(--ink); font-weight: 500; }

.about { padding: 14px 18px 22px; margin: 0; }
.about a { color: var(--muted); text-decoration: underline; text-decoration-color: var(--divider); text-underline-offset: 3px; }
.about a:hover { color: var(--accent); }
.grid2 { margin-top: 10px; }

/* Corner controls on the habitat: hide/show the UI, plus play/pause while it's hidden. */
#corner { position: absolute; top: 12px; right: 12px; z-index: 6; display: flex; gap: 8px; }
#corner button {
  width: 42px; height: 42px; padding: 0; font-size: 20px; line-height: 1; border-radius: 8px;
  background: rgba(18,16,14,0.85); color: var(--muted); opacity: 0.7; transition: opacity 0.15s;
}
#corner button:hover, #corner button:focus-visible { opacity: 1; color: var(--ink); }
#cornerplay { display: none; }
#helpbtn { font-family: var(--sans); font-weight: 600; }

body.collapsed #side, body.collapsed #bottom, body.collapsed #hud { display: none; }
body.collapsed #stage { position: fixed; inset: 0; width: auto; height: auto; }
body.collapsed #cornerplay { display: block; }
body.collapsed { overflow: hidden; }

/* Mid-width windows: a slimmer panel so the habitat keeps most of the screen. */
@media (max-width: 1280px) {
  :root { --side: 430px; --bottom: 160px; }
  html, body { font-size: 19px; }
  button, select, input[type=number], input[type=text] { font-size: 18px; }
  .ctrl { grid-template-columns: 116px 1fr 64px; gap: 10px; }
  .hint { font-size: 15px; }
}

/* Narrow screens (phones, split-screen): stack the habitat, the sparklines, and the
   controls vertically and let the page scroll. The habitat uses svh so a mobile URL
   bar sliding in and out doesn't resize (and rescale) the world. */
@media (max-width: 900px) {
  html, body { height: auto; overflow-x: hidden; overflow-y: auto; font-size: 16px; }
  #stage { position: relative; right: auto; bottom: auto; width: 100%; height: 62vh; height: 62svh; }
  #bottom { position: relative; width: 100%; height: auto; display: grid; grid-template-columns: repeat(3, 1fr); gap: 0; }
  .spark { height: 92px; border-bottom: 1px solid var(--divider); }
  .spark .val { font-size: 15px; }
  #side { position: static; width: 100%; height: auto; border-left: none; overflow: visible; }
  section { padding: 14px 16px; }
  section > h2 { font-size: 15px; }
  button, select, input[type=number], input[type=text] { font-size: 16px; }   /* 16px: iOS won't zoom on focus */
  .ctrl { grid-template-columns: 104px 1fr 56px; gap: 10px; }
  .hint { font-size: 14px; }
  #hud { font-size: 13px; top: 10px; left: 12px; right: 12px; }
  #starthint { font-size: 15px; }
  #corner { top: 8px; right: 8px; }
  #hud { right: 110px; }
  #tooltip { font-size: 14px; padding: 9px 12px; }
}

/* fast-forward speed row */
.seg.speed { margin-top: 8px; }
.seg.speed button { padding: 5px 0; font-size: 16px; }

/* First-visit guide. A modal over the running habitat; reopened with ? */
#welcome {
  width: min(720px, calc(100vw - 32px)); max-height: calc(100vh - 48px); max-height: calc(100svh - 48px); overflow-y: auto;
  padding: 28px 34px 24px; color: var(--ink); background: var(--panel);
  border: 1px solid var(--divider); border-radius: 10px; box-shadow: 0 12px 48px rgba(0,0,0,0.6);
  font-family: var(--sans); font-size: 17px; line-height: 1.55;
}
#welcomex { position: absolute; top: 14px; right: 14px; width: 40px; height: 40px; padding: 0; font-family: var(--sans); font-size: 24px; line-height: 1; color: var(--muted); }
#welcome::backdrop { background: rgba(10,9,8,0.55); }
#welcome h1 { font-size: 30px; font-weight: 600; letter-spacing: 0.04em; margin: 0; outline: none; }
#welcome .lede { color: var(--accent); margin: 2px 0 14px; }
#welcome h2 { font-size: 14px; font-weight: 600; letter-spacing: 0.14em; text-transform: uppercase; color: var(--muted); margin: 22px 0 6px; }
#welcome p { margin: 0 0 8px; }
#welcome ul { margin: 0; padding-left: 20px; }
#welcome li { margin: 0 0 7px; }
#welcome b { font-weight: 600; color: #EDE6DC; }
#welcome i { color: var(--muted); }
#welcome .keys { font-family: var(--mono); font-size: 14px; color: var(--muted); margin-top: 16px; }
#welcome kbd { font-size: 13px; }
#welcome .wfoot { display: flex; align-items: center; gap: 16px; flex-wrap: wrap; margin-top: 18px; color: var(--muted); font-size: 15px; }
#welcome .wfoot button { font-family: var(--sans); font-size: 17px; padding: 9px 20px; }
#welcome .coarse { display: none; }
@media (pointer: coarse) { #welcome .fine { display: none; } #welcome .coarse { display: list-item; } }
@media (max-width: 900px) {
  #welcome { padding: 20px 20px 18px; font-size: 15px; }
  #welcome h1 { font-size: 24px; }
}

/* species leaderboard */
.board { display: flex; flex-direction: column; gap: 2px; }
.brow { display: grid; grid-template-columns: 26px 26px 1fr 64px 64px; align-items: center; gap: 10px; padding: 3px 0; font-size: 17px; }
.brow canvas { width: 26px; height: 26px; }
.brow .rank { color: var(--muted); text-align: right; }
.brow .bname { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.brow .bnum { text-align: right; }
.brow .bnum.extinct { color: var(--muted); }
.brow.bhead { color: var(--muted); font-size: 13px; text-transform: uppercase; letter-spacing: 0.06em; padding-bottom: 4px; }
.brow.bhead span:nth-child(4), .brow.bhead span:nth-child(5) { text-align: right; }
@media (max-width: 1280px) { .brow { font-size: 15px; grid-template-columns: 22px 26px 1fr 54px 54px; gap: 8px; } }
@media (max-width: 900px) { .brow { font-size: 14px; } }

/* error banner: a caught error pauses the run and shows copyable details */
#errorbar {
  position: absolute; top: 60px; left: 50%; transform: translateX(-50%); z-index: 8; display: none;
  width: min(640px, calc(100% - 32px)); padding: 14px 16px; border-radius: 8px;
  background: rgba(23,20,15,0.97); border: 1px solid #A0473A; box-shadow: 0 8px 28px rgba(0,0,0,0.55);
  font-family: var(--sans); font-size: 16px; line-height: 1.45; color: var(--ink);
}
#errorbar b { display: block; color: #E08A7A; margin-bottom: 4px; }
#errorbar span { color: var(--muted); }
#errorbar pre { margin: 10px 0; max-height: 180px; overflow: auto; white-space: pre-wrap; word-break: break-word; font-family: var(--mono); font-size: 13px; color: var(--ink); background: var(--ground); border: 1px solid var(--divider); border-radius: 4px; padding: 8px 10px; }
#errorbar button { font-size: 15px; padding: 6px 12px; }