:root {
  color-scheme: light dark;
  --bg: #fafafa;
  --fg: #222;
  --muted: #667;
  --border: #ccc;
  --accent: #3563b8;
  --output-bg: #fff;
  --warning: #a05a00;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #16181c;
    --fg: #e6e6e6;
    --muted: #9aa;
    --border: #444;
    --accent: #7fa7e8;
    --output-bg: #0d0f12;
    --warning: #e0a04a;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0 auto;
  padding: 1.5rem 1rem 3rem;
  max-width: 60rem;
  background: var(--bg);
  color: var(--fg);
  font-family: system-ui, -apple-system, "Segoe UI", "Hiragino Sans", "Noto Sans JP", sans-serif;
  line-height: 1.6;
}

a { color: var(--accent); }

h1 { margin: 0 0 0.25rem; font-size: 1.6rem; }
.desc { margin: 0 0 1.25rem; color: var(--muted); font-size: 0.9rem; }

textarea {
  width: 100%;
  padding: 0.6rem;
  font: inherit;
  color: inherit;
  background: var(--output-bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  resize: vertical;
}

.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1.25rem;
  align-items: center;
  margin: 0.75rem 0;
  font-size: 0.9rem;
}
.controls select {
  font: inherit;
  color: inherit;
  background: var(--output-bg);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 0.2rem 0.3rem;
}
.controls .check { user-select: none; }

#status { min-height: 1.5em; margin: 0.25rem 0; color: var(--muted); font-size: 0.85rem; }
#status.error { color: #c0392b; }
.warning { margin: 0.25rem 0; color: var(--warning); font-size: 0.85rem; }

.output-wrap { position: relative; margin-top: 0.5rem; }

#copy {
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  padding: 0.3rem 0.9rem;
  font: inherit;
  font-size: 0.85rem;
  color: inherit;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  cursor: pointer;
}
#copy:hover { border-color: var(--accent); }

#output {
  min-height: 8rem;
  margin: 0;
  padding: 1rem;
  overflow: auto;
  background: var(--output-bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  font-family: ui-monospace, "Cascadia Mono", Consolas, "Courier New", monospace;
  font-size: 14px;
  line-height: 1;
  letter-spacing: 0;
}

footer {
  margin-top: 2.5rem;
  border-top: 1px solid var(--border);
  padding-top: 0.75rem;
  color: var(--muted);
  font-size: 0.8rem;
}