/* Colors are defined once here, light and dark. app.js reads them too, so the
   canvases follow the same theme. */
:root {
  color-scheme: light;
  --page: #f9f9f7;
  --surface: #fcfcfb;
  --text: #0b0b0b;
  --text-2: #52514e;
  --muted: #898781;
  --grid: #e1e0d9;
  --border: rgba(11, 11, 11, 0.10);
  --paper: #ffffff;        /* drawing pad and pixel grids */
  --ink: #0b0b0b;          /* the drawn digit */
  --accent: #2a78d6;       /* bars, buttons */
  --seq-low: #f0efec;      /* inactive neuron */
  --seq-high: #104281;     /* very active neuron */
  --div-neg: #e34948;      /* weight: wants this spot empty */
  --div-mid: #f0efec;      /* weight: doesn't care */
  --div-pos: #1c5cab;      /* weight: wants ink here */
  --good: #006300;         /* right guess (always with a check mark) */
  --bad: #d03b3b;          /* wrong guess (always with a cross) */
}
@media (prefers-color-scheme: dark) {
  :root {
    color-scheme: dark;
    --page: #0d0d0d;
    --surface: #1a1a19;
    --text: #ffffff;
    --text-2: #c3c2b7;
    --muted: #898781;
    --grid: #2c2c2a;
    --border: rgba(255, 255, 255, 0.10);
    --paper: #0d0d0d;
    --ink: #ffffff;
    --accent: #3987e5;
    --seq-low: #2c2c2a;
    --seq-high: #9ec5f4;
    --div-neg: #e66767;
    --div-mid: #383835;
    --div-pos: #6da7ec;
    --good: #0ca30c;
    --bad: #e66767;
  }
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
body {
  margin: 0;
  background: var(--page);
  color: var(--text);
  font: 16px/1.55 system-ui, -apple-system, "Segoe UI", sans-serif;
}
main { max-width: 900px; margin: 0 auto; padding: 32px 16px 48px; }
h1 { font-size: clamp(28px, 6vw, 40px); line-height: 1.15; margin: 0 0 12px; }
h2 { font-size: 22px; margin: 0 0 8px; display: flex; align-items: center; gap: 12px; }
h3 { font-size: 18px; margin: 32px 0 4px; }
p { margin: 0 0 12px; }
.intro p { color: var(--text-2); font-size: 18px; max-width: 680px; }
.lead { color: var(--text-2); max-width: 680px; }

section {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 24px;
  margin: 24px 0;
}
.step {
  display: inline-grid; place-items: center;
  width: 32px; height: 32px; border-radius: 50%;
  background: var(--accent); color: #fff; font-size: 16px; flex: none;
}
figure { margin: 0; display: flex; flex-direction: column; align-items: center; gap: 8px; }
figcaption { color: var(--text-2); font-size: 14px; text-align: center; }
.arrow { color: var(--muted); font-size: 28px; align-self: center; padding-bottom: 28px; }
canvas { display: block; }

/* 1. Draw */
.draw-layout { display: flex; flex-wrap: wrap; gap: 32px; align-items: flex-start; margin-top: 16px; }
.pad-column { width: min(100%, 320px); }
.pad-wrap { position: relative; }
#pad {
  width: 100%; aspect-ratio: 1; height: auto;
  background: var(--paper);
  border: 2px solid var(--grid);
  border-radius: 12px;
  touch-action: none;   /* drawing on a phone must not scroll the page */
  cursor: crosshair;
}
.pad-hint {
  position: absolute; inset: 0; margin: 0;
  display: grid; place-items: center;
  color: var(--muted); pointer-events: none;
}
.buttons { display: flex; gap: 8px; margin-top: 12px; }
button {
  flex: 1; font: inherit; font-weight: 600; cursor: pointer;
  padding: 10px 14px; border-radius: 10px;
  border: 1px solid var(--border); background: var(--page); color: var(--text);
}
button:hover { border-color: var(--accent); }
#example { background: var(--accent); border-color: var(--accent); color: #fff; }
.note { color: var(--text-2); font-size: 14px; margin-top: 10px; min-height: 1.5em; }

.result { flex: 1; min-width: 260px; }
.guess-label { color: var(--text-2); margin: 0; }
.guess { font-size: 96px; font-weight: 700; line-height: 1; margin: 4px 0 8px; }
.sure { color: var(--text-2); min-height: 3em; }
.bars { display: flex; gap: 2px; height: 160px; margin-top: 8px; }
.bar { flex: 1; display: flex; flex-direction: column; align-items: center; }
.bar-value { font-size: 12px; color: var(--text-2); height: 18px; font-variant-numeric: tabular-nums; }
.bar-track { flex: 1; width: 100%; display: flex; align-items: flex-end; justify-content: center; border-bottom: 1px solid var(--grid); }
.bar-fill { width: min(24px, 80%); background: var(--accent); border-radius: 4px 4px 0 0; transition: height 0.12s; }
.bar-digit { font-weight: 600; margin-top: 4px; }
.bar.top .bar-digit { color: var(--accent); }
.caption { color: var(--muted); font-size: 13px; margin-top: 6px; }

/* 2. What the computer sees */
.pipeline { display: flex; gap: 12px; align-items: flex-start; justify-content: center; margin: 20px 0; }
.pipeline canvas { width: min(168px, 34vw); height: auto; border-radius: 8px; background: var(--paper); border: 1px solid var(--grid); }
.strip-figure canvas { width: 100%; height: 80px; background: var(--paper); border: 1px solid var(--grid); border-radius: 8px; }
.strip-figure figcaption { max-width: 560px; }

/* 3. Inside the network */
.network { display: flex; flex-wrap: wrap; gap: 12px; align-items: flex-start; justify-content: center; margin: 20px 0 8px; }
#net-input { width: 112px; height: 112px; border-radius: 6px; border: 1px solid var(--grid); }
#net-hidden { width: min(256px, 80vw); height: auto; border-radius: 6px; }
.outputs { display: grid; grid-template-columns: auto 72px 40px; gap: 2px 6px; align-items: center; font-size: 13px; }
.outputs .digit { font-weight: 600; text-align: right; }
.outputs .track { height: 10px; }
.outputs .fill { height: 100%; background: var(--accent); border-radius: 0 4px 4px 0; }
.outputs .pct { color: var(--text-2); font-variant-numeric: tabular-nums; }
.outputs .top .digit, .outputs .digit.top { color: var(--accent); }

.key { display: inline-block; width: 10px; height: 10px; border-radius: 2px; margin-right: 4px; vertical-align: baseline; }
.key-pos { background: var(--div-pos); }
.key-neg { background: var(--div-neg); }
.neurons { display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; margin-top: 12px; }
.neuron { border: 1px solid var(--border); border-radius: 12px; padding: 12px; background: var(--page); }
.neuron-images { display: flex; gap: 6px; }
.neuron-images canvas { width: 50%; aspect-ratio: 1; height: auto; border-radius: 6px; }
.neuron-title { font-weight: 600; margin: 8px 0 2px; }
.neuron-meter { height: 6px; background: var(--seq-low); border-radius: 3px; margin: 4px 0 6px; }
.neuron-meter div { height: 100%; background: var(--accent); border-radius: 3px; }
.neuron-votes { font-size: 13px; color: var(--text-2); margin: 0; }
.empty { color: var(--muted); }

/* 4. How it learned */
.replay-controls { display: flex; gap: 12px; align-items: center; margin-top: 16px; }
.replay-controls button { flex: none; min-width: 108px; }
button.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
#replay-slider { flex: 1; accent-color: var(--accent); height: 28px; }
.replay-status { color: var(--text-2); margin-top: 8px; min-height: 3em; }
.replay-top { display: flex; flex-wrap: wrap; gap: 24px; align-items: flex-start; }
.replay-stat { width: 210px; }
.stat-value { font-size: 56px; font-weight: 700; line-height: 1; margin: 8px 0 4px; }
.stat-label { color: var(--text-2); font-size: 14px; }
.replay-chart { flex: 1; min-width: 260px; align-items: stretch; }
#replay-chart svg { display: block; width: 100%; overflow: visible; }
.chart-grid { stroke: var(--grid); stroke-width: 1; }
.chart-axis { stroke: var(--muted); stroke-width: 1; }
.chart-tick { fill: var(--muted); font-size: 12px; }
.chart-line { fill: none; stroke: var(--accent); stroke-width: 2; stroke-linejoin: round; stroke-linecap: round; }
.chart-area { fill: var(--accent); opacity: 0.1; }
.chart-now { stroke: var(--text-2); stroke-width: 1; }
.chart-dot { fill: var(--accent); stroke: var(--surface); stroke-width: 2; }
.replay-digits { display: grid; grid-template-columns: repeat(6, 1fr); gap: 10px; margin-top: 12px; }
.replay-digit { text-align: center; font-size: 13px; }
.replay-digit canvas, .replay-neurons canvas, .mistake canvas {
  width: 100%; aspect-ratio: 1; height: auto; border-radius: 6px; border: 1px solid var(--grid);
}
.replay-digit p { margin: 4px 0 0; color: var(--text-2); }
.verdict { font-weight: 600; }
.verdict.right { color: var(--good); }
.verdict.wrong { color: var(--bad); }
.replay-neurons { display: grid; grid-template-columns: repeat(8, 1fr); gap: 8px; margin-top: 12px; }

/* 5. Mistakes */
.confusion-wrap { margin: 12px 0 8px; max-width: 520px; }
.confusion-row { display: flex; align-items: center; gap: 6px; }
.axis-label { color: var(--muted); font-size: 13px; margin: 0 0 4px 52px; }
.axis-label.vertical { writing-mode: vertical-rl; margin: 0; }
.confusion { flex: 1; display: grid; grid-template-columns: repeat(11, 1fr); gap: 2px; font-size: 13px; }
.confusion .head { display: grid; place-items: center; font-weight: 600; color: var(--text-2); aspect-ratio: 1; }
.confusion .cell {
  aspect-ratio: 1; border: 0; padding: 0; border-radius: 4px; font: inherit; font-size: 12px;
  display: grid; place-items: center; background: var(--seq-low); color: var(--text);
}
.confusion .cell.diagonal { background: transparent; color: var(--muted); font-size: 10px; cursor: default; }
.confusion .cell.count { cursor: pointer; font-weight: 600; }
.confusion .cell.selected { outline: 2px solid var(--text); outline-offset: 1px; }
.mistakes-header { display: flex; align-items: baseline; justify-content: space-between; gap: 12px; margin-top: 24px; }
.mistakes-header h3 { margin: 0; }
.mistakes-header button { flex: none; }
.mistake-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(72px, 1fr)); gap: 10px; margin-top: 12px; }
.mistake { text-align: center; font-size: 12px; color: var(--text-2); }
.mistake p { margin: 4px 0 0; line-height: 1.3; }

/* 6. From 306 mistakes */
.steps { display: grid; grid-template-columns: minmax(0, 1fr) minmax(120px, 280px); gap: 16px 20px; margin: 16px 0 8px; align-items: center; }
.step-text p { margin: 0; }
.step-text .step-title { font-weight: 600; }
.step-text .step-detail { color: var(--text-2); font-size: 14px; }
.step-bar { display: flex; align-items: center; gap: 8px; }
.step-bar .fill { height: 20px; background: var(--accent); border-radius: 0 4px 4px 0; }
.step-bar .value { font-weight: 600; font-variant-numeric: tabular-nums; }

footer { color: var(--text-2); text-align: center; font-size: 14px; }

.tooltip {
  position: fixed; z-index: 10; pointer-events: none;
  background: var(--text); color: var(--page);
  font-size: 13px; padding: 6px 10px; border-radius: 8px;
  max-width: 240px;
}

@media (max-width: 560px) {
  section { padding: 18px 16px; }
  .arrow { transform: rotate(90deg); padding: 0; width: 100%; text-align: center; }
  .pipeline .arrow { width: auto; transform: none; }
  .guess { font-size: 72px; }
}
@media (max-width: 760px) {
  .neurons { grid-template-columns: 1fr 1fr; }
  .replay-digits { grid-template-columns: repeat(4, 1fr); }
  .replay-neurons { grid-template-columns: repeat(4, 1fr); }
  .steps { grid-template-columns: 1fr; gap: 6px; }
  .step-bar { margin-bottom: 12px; }
}