:root {
  --bg: #f7f7f7;
  --text: #222;
  --border: #ccc;
  --button-bg: #ffffff;
  --button-hover: #eeeeee;
  --link: #0066cc;
  --textarea-bg: #ffffff;
}

body.dark {
  --bg: #121212;
  --text: #eaeaea;
  --border: #333;
  --button-bg: #1e1e1e;
  --button-hover: #2a2a2a;
  --link: #4ea1ff;
  --textarea-bg: #1a1a1a;
}

* {
  box-sizing: border-box;
  font-family: system-ui, -apple-system, "Segoe UI", sans-serif;
}

body {
  margin: 0;
  padding: 16px;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  transition: 0.2s ease;
}

h1, h2, p {
  margin: 12px 0;
}

button {
  margin: 4px;
  padding: 8px 12px;
  border: 1px solid var(--border);
  background: var(--button-bg);
  color: var(--text);
  border-radius: 6px;
  cursor: pointer;
}

button:hover {
  background: var(--button-hover);
}

textarea {
  width: 100%;
  padding: 10px;
  margin: 8px 0;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--textarea-bg);
  color: var(--text);
  font-family: monospace;
  font-size: 14px;
  resize: vertical;
}

a {
  color: var(--link);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

@media (max-width: 768px) {
  button {
    width: 100%;
    margin: 6px 0;
  }
}

@media (max-width: 480px) {
  h1 { font-size: 20px; }
  h2 { font-size: 16px; }
}