:root {
  --bg: #fafafa;
  --fg: #1a1a1a;
  --muted: #666;
  --border: #d4d4d4;
  --accent: #0a66c2;
  --accent-fg: #fff;
  --panel: #ffffff;
  --code-bg: #f3f3f3;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft JhengHei UI", system-ui, sans-serif;
  font-size: 15px;
  line-height: 1.5;
}

header, footer {
  max-width: 1100px;
  margin: 0 auto;
  padding: 16px 20px;
}

header h1 {
  margin: 0 0 4px;
  font-size: 22px;
  font-weight: 600;
}

.hint { margin: 0; color: var(--muted); font-size: 13px; }

main {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 20px 24px;
  display: grid;
  grid-template-columns: minmax(320px, 1fr) minmax(320px, 1fr);
  gap: 20px;
}

@media (max-width: 820px) {
  main { grid-template-columns: 1fr; }
}

.panel {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 16px 18px;
}

.panel h2 {
  margin: 0 0 12px;
  font-size: 15px;
  font-weight: 600;
}

.row {
  display: grid;
  grid-template-columns: 110px 1fr;
  align-items: center;
  gap: 10px;
  margin-bottom: 10px;
}

.row.span2 { grid-template-columns: 110px 1fr; }

.row label {
  color: var(--muted);
  font-size: 13px;
}

.row select,
.row input[type="text"],
.row input[type="number"],
textarea {
  width: 100%;
  padding: 6px 8px;
  font: inherit;
  border: 1px solid var(--border);
  border-radius: 4px;
  background: #fff;
}

textarea {
  font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  font-size: 13px;
  resize: vertical;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 14px;
}

button {
  font: inherit;
  padding: 7px 14px;
  border: 1px solid var(--border);
  border-radius: 4px;
  background: #fff;
  cursor: pointer;
}

button:hover { border-color: #888; }

button.primary {
  background: var(--accent);
  color: var(--accent-fg);
  border-color: var(--accent);
}

button.primary:hover { filter: brightness(0.95); }

button.ghost { background: transparent; }

button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.status {
  min-height: 1.4em;
  margin: 10px 0 0;
  font-size: 13px;
  color: var(--muted);
}

.status.error { color: #b00020; }
.status.ok { color: #0a7a29; }

.preview-box {
  background: var(--code-bg);
  border: 1px dashed var(--border);
  border-radius: 4px;
  padding: 16px;
  min-height: 220px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.preview-box .empty {
  color: var(--muted);
  font-size: 13px;
}

.preview-box canvas,
.preview-box img,
.preview-box svg {
  max-width: 100%;
  height: auto;
  background: #fff;
  padding: 8px;
  border: 1px solid var(--border);
  border-radius: 3px;
}

footer {
  color: var(--muted);
  font-size: 12px;
  border-top: 1px solid var(--border);
  margin-top: 8px;
}