:root {
  color-scheme: dark;
  font: 16px/1.5 system-ui, sans-serif;
  background: #071522;
  color: #eaf3fa;
  --blue: #6fc7ff;
  --green: #70e4b2;
  --amber: #ffc26a;
  --muted: #aec2d0;
}

* { box-sizing: border-box; }
body { margin: 0; background: radial-gradient(at top right, #10374a, transparent 70%); }
header { display: flex; align-items: center; gap: 24px; border-bottom: 1px solid #294653; padding: 10px 24px; }
header span { margin-right: auto; color: var(--muted); }
a { color: var(--green); }
main { max-width: 1380px; margin: auto; padding: 18px 24px; }
.title-row { display: flex; align-items: baseline; justify-content: space-between; gap: 12px; }
h1 { font-size: 28px; letter-spacing: -.6px; margin: 0 0 12px; }
h2 { font-size: 22px; line-height: 1.25; margin: 0; }
h3 { font-size: 18px; margin: 0 0 10px; }
p { margin: 8px 0 14px; }
button, select, input { font: inherit; color: inherit; background: #142f41; border: 1px solid #365b70; border-radius: 7px; padding: 8px 11px; }
button { cursor: pointer; min-height: 38px; font-size: 14px; }
button:hover { background: #23485e; }
button:disabled { opacity: .45; cursor: default; }
button.selected, #run { background: #17413b; border-color: var(--green); }
button:focus-visible, select:focus-visible, input:focus-visible, #chart:focus-visible { outline: 2px solid var(--blue); outline-offset: 3px; }
.muted, dt { font-size: 14px; color: var(--muted); }
nav, .actions, .segmented { display: flex; gap: 7px; flex-wrap: wrap; }
nav { margin-bottom: 16px; }
#introduction { max-width: 900px; margin: 30px auto; padding: 20px 0; }
#introduction > h2 { font-size: 30px; max-width: 700px; }
#introduction > p { max-width: 780px; }
.intro-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; border-block: 1px solid #2a4859; padding: 22px 0; margin: 22px 0; }
.intro-grid strong { color: var(--green); font-size: 20px; }
.intro-grid p { margin: 6px 0 0; }
.lesson-copy { max-width: 1120px; margin-bottom: 16px; }
.lesson-copy p { margin: 7px 0 0; color: #c5d7e2; }
.workbench { display: grid; grid-template-columns: 245px minmax(0, 1fr); gap: 16px; }
.controls, .panel { min-width: 0; background: #0c2130; border: 1px solid #29495b; border-radius: 12px; padding: 15px; }
.controls { align-self: start; }
.controls > label { display: block; font-size: 14px; margin: 8px 0 5px; }
.controls > select { width: 100%; font-size: 14px; }
.controls > p.muted { margin: 4px 0 10px; overflow-wrap: anywhere; }
.setting-row { display: flex; justify-content: space-between; align-items: center; gap: 10px; margin: 9px 0; }
.setting-row label { font-size: 14px; }
.setting-row input { width: 96px; font-size: 14px; }
.setting-row select { font-size: 14px; }
#activationChoice { min-width: 108px; }
.activation-explanation { font-size: 12px; margin: 4px 0 8px; }
.training-actions { margin-top: 12px; }
.training-actions button { flex: 1; padding: 7px 8px; white-space: nowrap; }
#status { font-size: 14px; color: var(--green); min-height: 22px; margin: 9px 0; }
dl { margin: 0 0 10px; }
dl > div { display: flex; justify-content: space-between; gap: 8px; padding: 3px 0; }
dd { margin: 0; font-variant-numeric: tabular-nums; }
.controls details { margin-top: 10px; }
.controls details p { font-size: 14px; }
.results { min-width: 0; }
.combined-results { display: grid; grid-template-columns: minmax(0, 1fr); align-items: start; gap: 12px; }
.combined-results > .panel { min-width: 0; }
.workspace-details { display: grid; gap: 8px; margin-top: 10px; }
.workspace-details > details { min-width: 0; padding: 9px 12px; background: #0c2130; border: 1px solid #29495b; border-radius: 9px; }
.workspace-details > details[open] { padding-bottom: 12px; }
.workspace-details > details > .panel { margin-top: 9px; }
.panel-title { display: flex; align-items: center; justify-content: space-between; gap: 10px; }
.panel-title h3 { margin: 0; }
.legend { display: flex; gap: 14px; flex-wrap: wrap; font-size: 13px; margin: 8px 0; }
.train-key { color: var(--blue); }
.validation-key { color: var(--green); }
.best-key { color: var(--amber); }
.epoch-controls { margin: 4px 0; }
#chart { width: 100%; height: auto; max-height: 240px; display: block; touch-action: pan-y; }
.readout { font-variant-numeric: tabular-nums; font-size: 13px; min-height: 22px; color: #d4e1e9; margin: 4px 0 8px; }
.metric-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; border-top: 1px solid #2b485b; padding-top: 9px; }
.metric-grid span { font-size: 12px; color: var(--muted); display: block; }
.metric-grid strong { font-size: 16px; font-variant-numeric: tabular-nums; }
#metricStamp { font-size: 11px; margin: 4px 0; }
#curveHint { margin: 5px 0 9px; font-size: 12px; }
details { border-top: 1px solid #2b485b; padding-top: 8px; }
summary { cursor: pointer; color: var(--green); font-size: 13px; }
details p { font-size: 14px; }
details p:last-child { margin-bottom: 0; }
.checkpoint-panel { border-top: 1px solid #2b485b; padding-top: 9px; margin-top: 7px; }
.checkpoint-panel h3 { font-size: 15px; margin-bottom: 6px; }
.checkpoint-row { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; }
.checkpoint-row > div { margin-right: auto; }
.checkpoint-row span, .checkpoint-row strong { display: block; }
.checkpoint-row strong { font-size: 13px; }
.checkpoint-row button { min-height: 34px; padding: 6px 8px; }
#checkpointStatus { font-size: 11px; margin: 4px 0; }
.test-result { color: var(--green); font-size: 14px; font-variant-numeric: tabular-nums; margin: 4px 0; }
.sensitivity-panel h3 { font-size: 16px; }
.sensitivity-panel .panel-title { flex-wrap: wrap; }
.sensitivity-panel .panel-title > .muted { font-size: 11px; }
.sensitivity-explanation { font-size: 11px; margin: 4px 0; }
#sensitivityStamp { font-size: 11px; margin: 3px 0 7px; color: var(--muted); }
.sensitivity-row { display: grid; grid-template-columns: 60px minmax(0, 1fr) 62px; align-items: center; gap: 6px; width: 100%; border: 0; background: transparent; padding: 0 2px; min-height: 19px; font-size: 11px; text-align: left; border-radius: 3px; }
.sensitivity-row > span:last-child { text-align: right; font-variant-numeric: tabular-nums; color: var(--muted); }
.sensitivity-track { height: 7px; background: #1b3545; display: block; border-radius: 2px; overflow: hidden; }
.sensitivity-track > span { height: 100%; display: block; background: var(--amber); }
#sensitivityReadout { font-size: 11px; margin: 4px 0; }
.sensitivity-panel details { padding-top: 6px; }
.mistake-panel { margin-top: 2px; }
.mistake-layout { display: grid; grid-template-columns: minmax(330px, 1fr) minmax(220px, .65fr); gap: 24px; align-items: start; }
.matrix-wrap { overflow-x: auto; }
table { border-collapse: separate; border-spacing: 3px; width: 100%; font-size: 14px; text-align: center; }
caption { color: var(--muted); font-size: 14px; caption-side: bottom; padding: 8px; }
th { font-weight: 500; color: var(--muted); }
td { padding: 0; }
td button { display: block; width: 100%; border-radius: 4px; min-height: 29px; padding: 4px 2px; border-color: transparent; font-size: 13px; }
td button.chosen { outline: 2px solid var(--amber); outline-offset: -2px; }
.digit-inspector canvas { width: 120px; height: 120px; background: black; image-rendering: pixelated; border: 1px solid #365b70; display: block; }
.digit-inspector p { font-size: 14px; margin: 8px 0; }
.probability { display: grid; grid-template-columns: 15px 1fr 40px; gap: 6px; font-size: 13px; align-items: center; margin: 3px 0; }
.probability .track { background: #193447; border-radius: 3px; height: 8px; overflow: hidden; }
.probability .fill { height: 100%; background: var(--blue); }
.probability.correct .fill { background: var(--green); }
[hidden] { display: none !important; }

@media (min-width: 850px) and (max-height: 800px) {
  header { padding-top: 7px; padding-bottom: 7px; }
  main { padding-top: 6px; }
  h1 { margin-bottom: 6px; }
  nav { margin-bottom: 6px; }
  .lesson-copy { margin-top: 0; margin-bottom: 0; }
  .lesson-copy h2 { font-size: 18px; line-height: 1.1; }
  .combined-workbench { grid-template-columns: 220px minmax(0, 1fr); gap: 12px; }
  .combined-workbench .controls { max-height: calc(100dvh - 165px); overflow-y: auto; scrollbar-gutter: stable; padding: 8px; }
  .combined-workbench .controls > label { margin: 4px 0 2px; }
  .combined-workbench .setting-row { margin: 4px 0; }
  .combined-workbench .training-actions { margin-top: 6px; }
  .combined-workbench #status { min-height: 18px; margin: 4px 0; }
  .combined-workbench dl { margin-bottom: 4px; }
  .combined-workbench .controls details { margin-top: 6px; }
  .combined-results { grid-template-columns: minmax(0, 1fr); gap: 9px; }
  .combined-results > .panel { padding: 10px; }
  #chart { max-height: 190px; }
  .sensitivity-row { min-height: 18px; grid-template-columns: 55px minmax(0, 1fr) 58px; gap: 5px; font-size: 10px; }
  .combined-results .legend { gap: 8px; font-size: 11px; }
  .checkpoint-row { gap: 5px; }
  .checkpoint-row button { font-size: 12px; }
}

@media (max-width: 850px) {
  .combined-workbench { grid-template-columns: minmax(0, 1fr); gap: 12px; }
  .combined-results { grid-template-columns: minmax(0, 1fr); }
  .sensitivity-panel { display: block; }
  .mistake-layout { grid-template-columns: 1fr; }
  .digit-inspector { display: grid; grid-template-columns: 100px 1fr; gap: 10px; }
  .digit-inspector canvas { width: 100px; height: 100px; }
  .digit-inspector #probabilities { grid-column: 2; grid-row: 1 / 4; }
  .digit-inspector p { grid-column: 1; }
  .legend { gap: 9px; }
}

@media (max-width: 720px) {
  header { padding: 10px 14px; gap: 12px; }
  main { padding: 14px; }
  .workbench, .combined-workbench, .combined-results { grid-template-columns: minmax(0, 1fr); }
  .combined-workbench .controls { max-height: none; overflow: visible; }
  .intro-grid { grid-template-columns: 1fr; gap: 16px; }
  .controls { width: 100%; }
  nav button { flex: 1; white-space: nowrap; }
  .panel-title { align-items: flex-start; }
  .metric-grid { grid-template-columns: 1fr; gap: 5px; }
  #chart { min-height: 180px; }
  .mistake-layout { grid-template-columns: 1fr; }
  .title-row h1 { font-size: 26px; }
  #introduction { margin: 15px auto; }
  .sensitivity-row { min-height: 27px; font-size: 12px; grid-template-columns: 70px minmax(0, 1fr) 65px; }
}