:root {
  --bg: #f4f5f7;
  --panel: #ffffff;
  --text: #1c2330;
  --muted: #5d6778;
  --border: #d9dde4;
  --accent: #2f6fed;
  --accent-text: #ffffff;
  --warn-bg: #fff4e0;
  --warn-text: #7a4a00;
  --viewer: #e9ecf1;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #12151b;
    --panel: #1b2029;
    --text: #e6e9ef;
    --muted: #97a1b3;
    --border: #2e3542;
    --accent: #5b8def;
    --accent-text: #0b1020;
    --warn-bg: #3a2c12;
    --warn-text: #ffd89a;
    --viewer: #161a21;
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }
html, body { margin: 0; height: 100%; }
body {
  background: var(--bg);
  color: var(--text);
  font: 14px/1.4 system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
  display: flex;
  flex-direction: column;
}
header { padding: 10px 16px; border-bottom: 1px solid var(--border); background: var(--panel); }
h1 { margin: 0; font-size: 18px; font-weight: 650; }
h1 span { font-weight: 400; color: var(--muted); font-size: 14px; margin-left: 6px; }
h2 { font-size: 14px; margin: 16px 0 6px; }

main {
  flex: 1;
  min-height: 0;
  display: grid;
  grid-template-columns: 320px 1fr 300px;
}
#form, #side { overflow-y: auto; background: var(--panel); padding: 8px 14px 20px; }
#form { border-right: 1px solid var(--border); }
#side { border-left: 1px solid var(--border); }

fieldset { border: 0; border-bottom: 1px solid var(--border); margin: 0; padding: 10px 0 12px; }
legend { font-weight: 650; padding: 0; margin-bottom: 6px; }
label { display: block; margin: 6px 0; color: var(--muted); font-size: 13px; }
label.inline { display: flex; align-items: center; gap: 8px; }
label.check { display: flex; align-items: center; gap: 6px; color: var(--text); }
output { color: var(--text); font-weight: 600; float: right; }
input[type='number'], select {
  display: block;
  width: 100%;
  margin-top: 3px;
  padding: 5px 7px;
  font: inherit;
  color: var(--text);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
}
label.inline input { width: 90px; margin: 0; }
input[type='range'] { width: 100%; accent-color: var(--accent); }
input[type='checkbox'], input[type='radio'] { accent-color: var(--accent); }
.grid2 { display: grid; grid-template-columns: 1fr 1fr; gap: 0 10px; }
.seg label { display: flex; gap: 6px; color: var(--text); }
.hint { color: var(--muted); font-size: 12px; margin: 6px 0; }
.callout { background: var(--bg); border: 1px solid var(--border); border-radius: 6px; padding: 8px; font-size: 13px; margin-top: 8px; }
.only-double { display: none; }
form.double .only-double { display: block; }
.bed-custom { display: none; }
.only-open, .only-grid, .only-key, .only-splice, .only-key-block { display: none; }
form.joint-key .only-key-block { display: flex; }
form.front-open .only-open { display: block; }
form.front-grid .only-grid, form.joint-key .only-key, form.joint-splice .only-splice { display: grid; }
form.front-open .not-open { display: none; }
form.custom-bed .bed-custom { display: grid; }

#viewer { position: relative; min-width: 0; min-height: 0; background: var(--viewer); }
#canvas { position: absolute; inset: 0; }
#status {
  position: absolute; left: 12px; top: 12px;
  background: var(--panel); border: 1px solid var(--border); border-radius: 6px;
  padding: 4px 8px; font-size: 12px; color: var(--muted);
}
#status.error { color: #d33; }
.view-tools {
  position: absolute; left: 12px; bottom: 12px; right: 12px;
  display: flex; flex-wrap: wrap; gap: 6px; align-items: center;
}
.view-tools label.check { margin: 0 0 0 6px; background: var(--panel); padding: 4px 8px; border-radius: 6px; border: 1px solid var(--border); }

button {
  font: inherit; color: var(--text); background: var(--panel);
  border: 1px solid var(--border); border-radius: 6px; padding: 6px 10px; cursor: pointer;
}
button:hover:not(:disabled) { border-color: var(--accent); }
button:disabled { opacity: 0.5; cursor: default; }
button.primary { background: var(--accent); color: var(--accent-text); border-color: var(--accent); font-weight: 600; }
.downloads { display: grid; gap: 8px; padding-top: 8px; }

dl { display: grid; grid-template-columns: auto 1fr; gap: 3px 10px; margin: 14px 0 0; font-size: 13px; }
dt { color: var(--muted); }
dd { margin: 0; text-align: right; font-variant-numeric: tabular-nums; }
#warnings { list-style: none; padding: 0; margin: 10px 0 0; }
#warnings li { background: var(--warn-bg); color: var(--warn-text); border-radius: 6px; padding: 6px 8px; margin-bottom: 6px; font-size: 12.5px; }
#parts { list-style: none; padding: 0; margin: 0; }
#parts li { display: flex; align-items: center; gap: 8px; padding: 5px 0; border-bottom: 1px solid var(--border); font-size: 13px; }
#parts .sw { width: 12px; height: 12px; border-radius: 3px; flex: none; }
#parts .nm { flex: 1; min-width: 0; }
#parts .nm small { display: block; color: var(--muted); font-variant-numeric: tabular-nums; }
#parts button { padding: 3px 7px; font-size: 12px; }
details { margin-top: 16px; }
summary { cursor: pointer; font-weight: 650; }
.help { padding-left: 18px; color: var(--muted); font-size: 12.5px; }

@media (max-width: 1000px) {
  main { display: flex; flex-direction: column; overflow-y: auto; }
  #viewer { order: -1; flex: none; height: 55vh; }
  #form, #side { border: 0; overflow: visible; padding: 8px 16px 20px; }
}