:root {
  --bg: #f5f5f7;
  --card-bg: #ffffff;
  --text: #222222;
  --accent: #2222aa;
  --border: #dddddd;
  --fixed: #cccccc;
  --black-cell: #111111;
  --white-cell: #ffffff;
  --grid-line: #e0e0e0;
  --error: #b00020;
  --shadow: 0 4px 14px rgba(0,0,0,0.08);
  --radius: 12px;
  --qr-size: 260px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: radial-gradient(circle at top, #fdfdfd, #ececf2);
  color: var(--text);
}

.page-header, .page-footer {
  text-align: center;
  padding: 1.2rem 1rem;
}

.page-header h1 {
  margin: 0;
  font-size: 1.8rem;
  letter-spacing: 0.03em;
}

.page-header p {
  margin: 0.4rem 0 0;
  color: #555;
}

.page-footer {
  font-size: 0.85rem;
  color: #777;
}

.main {
  max-width: 1060px;
  margin: 0 auto 2rem;
  padding: 0 1rem 1rem;
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) minmax(0, 1fr);
  gap: 1rem;
}

.card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 1rem 1.2rem;
  box-shadow: var(--shadow);
  border: 1px solid rgba(0,0,0,0.03);
}

.intro {
  grid-column: 1 / -1;
}

.generator {
  grid-column: 1 / 2;
}

.preview, .grid-section {
  grid-column: 2 / 3;
}

@media (max-width: 900px) {
  .main {
    grid-template-columns: 1fr;
  }
  .preview, .grid-section {
    grid-column: 1 / -1;
  }
}

h2 {
  margin-top: 0;
  font-size: 1.2rem;
}

label {
  display: block;
  margin-bottom: 0.3rem;
  font-weight: 600;
}

textarea {
  width: 100%;
  resize: vertical;
  min-height: 60px;
  padding: 0.6rem;
  border-radius: 8px;
  border: 1px solid var(--border);
  font-family: inherit;
}

textarea:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 2px rgba(34, 34, 170, 0.12);
}

button {
  margin-top: 0.7rem;
  padding: 0.6rem 1.2rem;
  border-radius: 999px;
  border: none;
  background: var(--accent);
  color: white;
  font-weight: 600;
  cursor: pointer;
}

button:hover {
  filter: brightness(1.05);
}

.hint {
  margin-top: 0.4rem;
  font-size: 0.85rem;
  color: #666;
}

.error {
  margin-top: 0.5rem;
  color: var(--error);
  font-size: 0.9rem;
  min-height: 1.1em;
}

.qr-preview {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: var(--qr-size);
  border-radius: 10px;
  border: 1px dashed var(--border);
  background: #fafafa;
}

.qr-preview svg {
  width: var(--qr-size);
  height: var(--qr-size);
}

.placeholder {
  color: #888;
  font-size: 0.9rem;
}

.grid-container {
  margin-top: 0.6rem;
  display: inline-block;
  border: 1px solid var(--border);
  padding: 6px;
  border-radius: 10px;
  background: #fafafa;
}

.qr-grid {
  display: grid;
  grid-template-columns: repeat(25, 1fr);
  gap: 1px;
}

.qr-cell {
  width: 14px;
  height: 14px;
  border-radius: 2px;
  border: 1px solid var(--grid-line);
}

.qr-cell.fixed {
  background: var(--fixed);
}

.qr-cell.data-black {
  background: var(--black-cell);
}

.qr-cell.data-white {
  background: var(--white-cell);
}

.counts {
  font-size: 0.9rem;
  color: #444;
}

.legend {
  display: inline-block;
  width: 14px;
  height: 14px;
  border-radius: 3px;
  margin-right: 4px;
  vertical-align: middle;
}

.legend-fixed {
  background: var(--fixed);
}

.legend-black {
  background: var(--black-cell);
}

.legend-white {
  background: var(--white-cell);
  border: 1px solid var(--grid-line);
}