* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  padding: 32px 16px;
  color: #1f2937;
  background: #f3f4f6;
  font-family: Arial, sans-serif;
}

.app {
  width: min(100%, 620px);
  margin: 0 auto;
  padding: 28px;
  text-align: center;
  background: #ffffff;
  border-radius: 16px;
  box-shadow: 0 8px 30px rgb(0 0 0 / 10%);
}

h1 {
  margin: 0 0 12px;
  font-size: clamp(1.7rem, 5vw, 2.3rem);
}

.hint, .example {
  margin: 8px 0;
  color: #6b7280;
  line-height: 1.5;
}

code {
  padding: 2px 5px;
  color: #374151;
  background: #e5e7eb;
  border-radius: 4px;
  overflow-wrap: anywhere;
}

.preview {
  margin: 24px auto 18px;
  max-width: 500px;
}

#boardCanvas {
  display: none;
}

#boardImage {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 4px;
}

.download {
  display: inline-block;
  padding: 11px 18px;
  color: #fff;
  background: #2563eb;
  border-radius: 8px;
  text-decoration: none;
  font-weight: bold;
}

.download:hover {
  background: #1d4ed8;
}

.status {
  min-height: 1.2em;
  margin: 16px 0 0;
  color: #6b7280;
  font-size: .9rem;
}