* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: system-ui, sans-serif;
  background: #f3f4f6;
  color: #111827;
}

.app-header {
  padding: 1rem 1.5rem;
  background: #1f2937;
  color: #fff;
}

.app-header h1 { margin: 0; font-size: 1.25rem; }
.app-header h3 { margin: 0; font-size: 0.85rem; }
.app-header h3 a { color: #fff; text-decoration: underline;}

.app-main {
  display: flex;
  gap: 1.5rem;
  padding: 1.5rem;
  align-items: flex-start;
}

.toolbar {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  width: 180px;
}

.toolbar button {
  padding: 0.6rem 0.75rem;
  border: 1px solid #d1d5db;
  border-radius: 6px;
  background: #fff;
  cursor: pointer;
  font-size: 0.9rem;
}

.toolbar button:hover { background: #e5e7eb; }

.canvas-area {
  background: #fff;
  padding: 1rem;
  border: 1px solid #d1d5db;
  border-radius: 8px;
  overflow: auto;
}