:root {
  color-scheme: light;
  --bg: #f5f6f2;
  --panel: #ffffff;
  --ink: #172025;
  --muted: #60707a;
  --line: #d9ded8;
  --green: #19715f;
  --green-soft: #dceee8;
  --blue: #315f91;
  --red: #b95a48;
  --amber: #d39a2f;
  --shadow: 0 18px 42px rgba(30, 40, 45, 0.10);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.78), rgba(255, 255, 255, 0.25)),
    var(--bg);
  color: var(--ink);
  font: 14px/1.45 Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

button,
input {
  font: inherit;
}

button {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  color: var(--ink);
  cursor: pointer;
  font-weight: 800;
  min-height: 40px;
  padding: 0 14px;
}

button:hover,
button:focus-visible {
  border-color: var(--green);
  outline: 2px solid rgba(25, 113, 95, 0.12);
}

h1,
h2,
p,
figure {
  margin: 0;
}

h1 {
  font-size: clamp(24px, 3vw, 36px);
  letter-spacing: 0;
  line-height: 1.08;
}

h2 {
  font-size: 18px;
  line-height: 1.2;
}

.app-shell {
  display: grid;
  gap: 16px;
  margin: 0 auto;
  max-width: 1540px;
  padding: 20px;
}

.topbar,
.section-title,
.score-summary {
  align-items: center;
  display: flex;
  gap: 14px;
  justify-content: space-between;
}

.eyebrow {
  color: var(--green);
  font-size: 12px;
  font-weight: 900;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.badges {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  justify-content: flex-end;
}

.badges span,
.stage,
.gallery-meta span {
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--muted);
  display: inline-flex;
  font-size: 12px;
  font-weight: 800;
  line-height: 1;
  padding: 8px 10px;
  white-space: nowrap;
}

.tabs {
  align-items: center;
  background: #e9ede7;
  border: 1px solid var(--line);
  border-radius: 8px;
  display: flex;
  gap: 4px;
  padding: 4px;
  width: max-content;
}

.tab-button {
  background: transparent;
  border-color: transparent;
}

.tab-button.active {
  background: #fff;
  border-color: var(--line);
  color: var(--green);
}

.tab-panel {
  display: none;
}

.tab-panel.active {
  display: block;
}

.panel {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: var(--shadow);
}

.demo-grid {
  align-items: start;
  display: grid;
  gap: 16px;
  grid-template-columns: 310px minmax(0, 1fr) 360px;
}

.controls,
.readout,
.canvases,
.explainer,
.explainer-visuals,
.score-summary,
.table-panel,
.failures {
  padding: 16px;
}

.controls,
.readout,
.canvases,
.explainer,
.explainer-visuals,
.score-layout,
.failures {
  display: grid;
  gap: 14px;
}

.dropzone {
  align-content: center;
  border: 1px dashed #98a8a6;
  border-radius: 8px;
  display: grid;
  gap: 10px;
  min-height: 118px;
  padding: 14px;
  text-align: center;
}

.dropzone.dragging {
  background: var(--green-soft);
  border-color: var(--green);
}

.file-input {
  height: 1px;
  opacity: 0;
  position: absolute;
  width: 1px;
}

.file-label {
  align-items: center;
  background: var(--green);
  border-radius: 8px;
  color: #fff;
  cursor: pointer;
  display: inline-flex;
  font-weight: 900;
  justify-content: center;
  min-height: 42px;
  padding: 0 16px;
}

.toggle {
  align-items: start;
  color: var(--muted);
  display: grid;
  gap: 8px;
  grid-template-columns: auto 1fr;
}

.search-row {
  display: grid;
  gap: 8px;
  grid-template-columns: 1fr auto;
}

.search-row input {
  border: 1px solid var(--line);
  border-radius: 8px;
  min-height: 40px;
  padding: 0 12px;
  width: 100%;
}

.gallery {
  display: grid;
  gap: 10px;
  max-height: 58vh;
  overflow: auto;
  padding-right: 4px;
}

.sample {
  align-items: center;
  display: grid;
  gap: 10px;
  grid-template-columns: 92px 1fr;
  min-height: 82px;
  padding: 8px;
  text-align: left;
  white-space: normal;
}

.sample.active {
  background: var(--green-soft);
  border-color: var(--green);
}

.sample img {
  aspect-ratio: 4 / 3;
  border-radius: 6px;
  height: 66px;
  object-fit: cover;
  width: 88px;
}

.sample strong,
.sample small {
  display: block;
  overflow-wrap: anywhere;
}

.sample > span {
  min-width: 0;
}

.sample small {
  color: var(--muted);
  font-weight: 700;
}

.gallery-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  margin-top: 4px;
}

.gallery-meta span {
  max-width: 100%;
  overflow: hidden;
  text-overflow: ellipsis;
}

.status-row {
  align-items: center;
  display: flex;
  gap: 12px;
  justify-content: space-between;
}

.stage-strip {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  justify-content: flex-end;
}

.stage.active {
  border-color: var(--amber);
  color: #8a5d14;
}

.stage.done {
  background: var(--green-soft);
  border-color: #b8d7cb;
  color: var(--green);
}

.canvas-grid {
  display: grid;
  gap: 14px;
  grid-template-columns: minmax(0, 1.35fr) minmax(280px, 0.85fr);
}

canvas {
  background: #eef1ed;
  border: 1px solid var(--line);
  border-radius: 8px;
  display: block;
  max-width: 100%;
}

#inputCanvas,
#rectCanvas {
  height: auto;
  width: 100%;
}

figcaption,
.note {
  color: var(--muted);
  font-size: 13px;
  margin-top: 8px;
}

.metric-grid {
  display: grid;
  gap: 8px;
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.metric-grid.wide {
  flex: 1;
  grid-template-columns: repeat(4, minmax(120px, 1fr));
}

.metric-grid div {
  border: 1px solid var(--line);
  border-radius: 8px;
  min-height: 66px;
  padding: 10px;
}

.metric-grid span {
  color: var(--muted);
  display: block;
  font-size: 12px;
  font-weight: 800;
}

.metric-grid strong {
  display: block;
  font-size: 20px;
  line-height: 1.25;
  margin-top: 4px;
}

.fen,
.grid-text,
.pseudo {
  background: #172025;
  border-radius: 8px;
  color: #f4f1e8;
  font: 12px/1.5 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  margin: 0;
  overflow: auto;
  padding: 12px;
  white-space: pre-wrap;
}

.board-diagram {
  aspect-ratio: 1;
  border: 1px solid var(--line);
  border-radius: 8px;
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  overflow: hidden;
}

.board-diagram span {
  align-items: center;
  display: flex;
  font: 800 16px/1 ui-monospace, monospace;
  justify-content: center;
  min-width: 0;
}

.board-diagram span.light {
  background: #eadfc5;
}

.board-diagram span.dark {
  background: #6d8677;
  color: #fff;
}

.board-diagram span.hit {
  box-shadow: inset 0 0 0 3px rgba(185, 90, 72, 0.38);
}

.explainer-grid {
  display: grid;
  gap: 16px;
  grid-template-columns: minmax(280px, 420px) minmax(0, 1fr);
}

.steps {
  display: grid;
  gap: 12px;
  margin: 0;
  padding-left: 20px;
}

.steps li {
  color: var(--muted);
}

.steps strong {
  color: var(--ink);
}

.mini-grid {
  display: grid;
  gap: 12px;
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.mini-grid canvas {
  height: auto;
  width: 100%;
}

.score-layout {
  grid-template-columns: 1fr;
}

.score-summary {
  flex-wrap: wrap;
}

.table-panel {
  overflow: auto;
}

table {
  border-collapse: collapse;
  min-width: 900px;
  width: 100%;
}

th,
td {
  border-bottom: 1px solid var(--line);
  padding: 10px;
  text-align: left;
  vertical-align: top;
}

th {
  color: var(--muted);
  font-size: 12px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.status-ok {
  color: var(--green);
  font-weight: 900;
}

.status-warn {
  color: var(--amber);
  font-weight: 900;
}

.status-bad {
  color: var(--red);
  font-weight: 900;
}

.failures {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.failures h2 {
  grid-column: 1 / -1;
}

.failures p {
  color: var(--muted);
}

@media (max-width: 1180px) {
  .demo-grid,
  .explainer-grid {
    grid-template-columns: 1fr;
  }

  .gallery {
    max-height: none;
  }
}

@media (max-width: 780px) {
  .app-shell {
    padding: 12px;
  }

  .topbar,
  .status-row,
  .score-summary {
    align-items: stretch;
    flex-direction: column;
  }

  .tabs {
    width: 100%;
  }

  .tab-button {
    flex: 1;
  }

  .canvas-grid,
  .mini-grid,
  .failures,
  .metric-grid.wide {
    grid-template-columns: 1fr;
  }
}