:root {
  --bg: #0b1220;
  --panel: #121a2b;
  --panel-border: #24324f;
  --text: #e2e8f0;
  --muted: #94a3b8;
  --accent: #60a5fa;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: Inter, system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  background: radial-gradient(1200px 700px at 20% -10%, #1e3a5f 0%, transparent 45%),
    linear-gradient(160deg, #070b12, var(--bg));
  color: var(--text);
  min-height: 100vh;
}

.app {
  width: min(1100px, calc(100% - 1.25rem));
  margin: 0.8rem auto;
  background: rgba(15, 23, 42, 0.65);
  border: 1px solid var(--panel-border);
  border-radius: 16px;
  padding: 1rem;
}

h1 {
  margin: 0 0 0.35rem;
  font-size: 1.35rem;
}

p.sub {
  margin: 0 0 0.9rem;
  color: var(--muted);
  font-size: 0.9rem;
}

.grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.9rem;
}

@media (min-width: 980px) {
  .grid {
    grid-template-columns: 340px 1fr;
  }
}

.panel {
  background: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: 12px;
  padding: 0.8rem;
}

label {
  display: block;
  margin: 0.55rem 0 0.25rem;
  font-size: 0.82rem;
  color: var(--muted);
}

input,
select,
button {
  width: 100%;
  border-radius: 10px;
  border: 1px solid #334155;
  background: #0f172a;
  color: var(--text);
  padding: 0.62rem 0.7rem;
  font-size: 0.9rem;
}

button {
  margin-top: 0.8rem;
  border-color: #3b82f6;
  background: linear-gradient(135deg, #2563eb, #60a5fa);
  color: white;
  font-weight: 600;
  cursor: pointer;
}

.preview-wrap {
  display: grid;
  place-items: center;
  min-height: 260px;
}

canvas {
  width: min(100%, 760px);
  height: auto;
  border-radius: 10px;
  border: 1px solid #334155;
  background: #0f172a;
}

.helper {
  color: var(--muted);
  font-size: 0.78rem;
  margin-top: 0.4rem;
}