* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Hiragino Sans', 'Noto Sans JP', 'Yu Gothic UI', 'Meiryo', Arial, sans-serif;
  color: #1b1f23;
  background: #f6f8fa;
}
header {
  padding: 16px 20px;
  background: #24292e;
  color: #fff;
}
header h1 { margin: 0 0 4px; font-size: 20px; }
header p { margin: 0; opacity: 0.85; }

.top-nav {
  display: flex;
  gap: 8px;
  padding: 8px 16px;
  border-bottom: 1px solid #e1e4e8;
  background: #f6f8fa;
}
.link-button {
  display: inline-block;
  padding: 6px 10px;
  font-size: 14px;
  color: #24292e;
  background: #fff;
  text-decoration: none;
  border: 1px solid #d1d5da;
  border-radius: 6px;
}
.link-button:hover { background: #f3f4f6; border-color: #c9d1d9; }

.container {
  display: grid;
  grid-template-columns: 360px 1fr;
  gap: 16px;
  padding: 16px;
}

.controls {
  background: #fff;
  border: 1px solid #e1e4e8;
  border-radius: 8px;
  padding: 12px;
}

.field-group {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 12px;
  margin-bottom: 12px;
}
.field-group.vertical { flex-direction: column; }

label { font-size: 12px; color: #586069; display: flex; flex-direction: column; gap: 6px; }
input[type="number"], input[type="color"], textarea {
  padding: 8px;
  font-size: 14px;
  border: 1px solid #d1d5da;
  border-radius: 6px;
  background: #fff;
  color: #24292e;
}
input[type="number"] { width: 110px; }
textarea { width: 100%; resize: vertical; }

.checkbox { flex-direction: row; align-items: center; gap: 8px; margin-left: 8px; }

.buttons { display: flex; gap: 8px; }
button {
  padding: 8px 12px;
  border: 1px solid #1f6feb;
  background: #2f81f7;
  color: #fff;
  border-radius: 6px;
  cursor: pointer;
}
button:hover { background: #1f6feb; }
button:active { transform: translateY(1px); }

.preview {
  background: #fff;
  border: 1px solid #e1e4e8;
  border-radius: 8px;
  padding: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: auto;
}

canvas { display: block; max-width: 100%; background: #639978; }

@media (max-width: 900px) {
  .container { grid-template-columns: 1fr; }
}

.hints {
  margin-top: 10px;
  padding: 10px 12px;
  border: 1px solid #e1e4e8;
  border-radius: 6px;
  background: #fffef2;
}
.hints-title {
  font-weight: 600;
  font-size: 13px;
  color: #5a5a00;
  margin-bottom: 6px;
}
.hints ul {
  margin: 0;
  padding-left: 18px;
}
.hints li { font-size: 12px; color: #57606a; line-height: 1.6; }