*, *::before, *::after { box-sizing: border-box; }
html, body { margin: 0; padding: 0; height: 100%; overflow: hidden; }
body {
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  background: #1a1a1a;
  color: #e0e0e0;
}
#app {
  display: grid;
  grid-template-columns: 320px 1fr;
  height: 100vh;
  width: 100vw;
}
#controls {
  background: #222;
  border-right: 1px solid #333;
  padding: 20px;
  overflow-y: auto;
}
#controls h1 {
  font-size: 18px;
  font-weight: 600;
  margin: 0 0 4px;
  letter-spacing: 0.5px;
}
#controls .status {
  font-size: 12px;
  color: #888;
  margin: 0 0 24px;
}
#controls .placeholder {
  font-size: 13px;
  color: #666;
  padding: 16px;
  border: 1px dashed #444;
  border-radius: 4px;
  text-align: center;
}
#viewport {
  position: relative;
  overflow: hidden;
}
#canvas3d {
  display: block;
  width: 100%;
  height: 100%;
}