*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --bg: #f5f5f5;
  --fg: #111;
  --code-bg: #e0e0e0;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #111;
    --fg: #eee;
    --code-bg: #222;
  }
}

[data-theme="light"] {
  --bg: #f5f5f5;
  --fg: #111;
  --code-bg: #e0e0e0;
}

[data-theme="dark"] {
  --bg: #111;
  --fg: #eee;
  --code-bg: #222;
}

body {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background: var(--bg);
  color: var(--fg);
  font-family: 'Courier New', monospace;
  transition: background 0.3s, color 0.3s;
}

.timer {
  font-size: clamp(5rem, 20vw, 12rem);
  font-weight: bold;
  letter-spacing: 0.05em;
  transition: color 0.7s;
}

.timer.done {
  color: #e74c3c;
}

.error {
  font-size: 1.2rem;
  color: #e74c3c;
  max-width: 90vw;
  text-align: center;
  padding: 0 1rem;
}

.error code {
  background: var(--code-bg);
  padding: 0.1em 0.4em;
  border-radius: 4px;
}

#app {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2rem;
}

.reset-button {
  font-size: 1.2rem;
  padding: 0.75rem 2rem;
  background: none;
  border: 2px solid var(--fg);
  color: var(--fg);
  cursor: pointer;
  border-radius: 8px;
  font-family: 'Courier New', monospace;
  transition: background 0.2s, color 0.2s;
}

.reset-button:hover {
  background: var(--fg);
  color: var(--bg);
}

.reset-button[hidden] {
  display: block;
  visibility: hidden;
  pointer-events: none;
}

.theme-toggle {
  position: fixed;
  top: 1rem;
  right: 1rem;
  background: none;
  border: none;
  cursor: pointer;
  color: var(--fg);
  padding: 0.5rem;
  border-radius: 50%;
  line-height: 0;
  opacity: 0.7;
  transition: opacity 0.2s;
}

.theme-toggle:hover {
  opacity: 1;
}