* { box-sizing: border-box; }
body {
  margin: 0; font: 14px/1.45 -apple-system, system-ui, sans-serif;
  color: #1d2330; background: #f4f6fa;
}
header { padding: 14px 20px; background: #1d2330; color: #fff; }
header h1 { margin: 0; font-size: 18px; letter-spacing: .5px; }
.ver { font-size: 11px; font-weight: 400; opacity: .65; background: #ffffff22; padding: 2px 7px; border-radius: 10px; margin-left: 8px; vertical-align: middle; }
header .sub { margin: 2px 0 0; font-size: 12px; opacity: .7; }

main { display: flex; gap: 18px; padding: 18px; align-items: flex-start; }

.canvas-wrap { flex: 0 0 auto; }
canvas {
  background: #fff; border: 1px solid #c7cedb; border-radius: 8px;
  cursor: crosshair; display: block; touch-action: none;
}
.hint { font-size: 12px; color: #6b7484; margin-top: 6px; }

.panel { flex: 1 1 260px; max-width: 320px; display: flex; flex-direction: column; gap: 12px; }
fieldset { border: 1px solid #d4dae6; border-radius: 8px; padding: 10px 12px; background: #fff; }
fieldset.operator { border-color: #b9a6e6; background: #faf7ff; }
legend { font-size: 12px; font-weight: 600; color: #4a5468; padding: 0 4px; }

label { display: flex; align-items: center; gap: 6px; margin: 6px 0; font-size: 13px; }
label input { margin-left: auto; width: 80px; padding: 4px 6px; border: 1px solid #c7cedb; border-radius: 5px; }
.unit { color: #889; font-size: 12px; width: 56px; }
.note { font-size: 11px; color: #8a93a3; margin-top: 4px; }

.row { display: flex; gap: 8px; }
button {
  flex: 1; padding: 8px 10px; border: 1px solid #c7cedb; background: #fff;
  border-radius: 6px; cursor: pointer; font-size: 13px;
}
button:hover { background: #eef1f7; }
button.primary { background: #5b3fd6; color: #fff; border-color: #5b3fd6; }
button.primary:hover { background: #4a32b8; }

.readout { font-size: 13px; background: #fff; border: 1px solid #d4dae6; border-radius: 8px; padding: 10px 12px; min-height: 40px; white-space: pre-wrap; }
.readout b { color: #5b3fd6; }