/* Design tokens — light mode (default) */
:root {
  color-scheme: light;
  --bg: #f5f4f1;
  --surface: #ffffff;
  --border: #e2ddd8;
  --text: #1c1917;
  --text-muted: #78716c;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --success-bg: #f0fdf4;
  --success-border: #86efac;
  --success-text: #166534;
  --error-bg: #fef2f2;
  --error-border: #fca5a5;
  --error-text: #991b1b;
  --radius-sm: 6px;
  --radius: 10px;
  --radius-lg: 14px;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.07), 0 1px 2px rgba(0, 0, 0, 0.04);
  --font-mono: 'SF Mono', 'Fira Code', 'Cascadia Code', ui-monospace, monospace;
}

/* Dark mode — OS preference (unless user explicitly chose light) */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme='light']) {
    color-scheme: dark;
    --bg: #0c0a09;
    --surface: #1c1917;
    --border: #292524;
    --text: #fafaf9;
    --text-muted: #a8a29e;
    --accent: #3b82f6;
    --accent-hover: #60a5fa;
    --success-bg: #052e16;
    --success-border: #166534;
    --success-text: #86efac;
    --error-bg: #450a0a;
    --error-border: #991b1b;
    --error-text: #fca5a5;
  }
}

/* Dark mode — explicit toggle */
[data-theme='dark'] {
  color-scheme: dark;
  --bg: #0c0a09;
  --surface: #1c1917;
  --border: #292524;
  --text: #fafaf9;
  --text-muted: #a8a29e;
  --accent: #3b82f6;
  --accent-hover: #60a5fa;
  --success-bg: #052e16;
  --success-border: #166534;
  --success-text: #86efac;
  --error-bg: #450a0a;
  --error-border: #991b1b;
  --error-text: #fca5a5;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
a {
  color: var(--accent);
}
a:hover {
  color: var(--accent-hover);
}

.wrapper {
  max-width: 640px;
  margin: 0 auto;
  padding: 2.5rem 1.25rem 5rem;
}

/* Card — shared structure */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow);
  margin-bottom: 1rem;
}

/* Theme toggle */
.btn-theme {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.25rem;
  height: 2.25rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface);
  color: var(--text-muted);
  cursor: pointer;
  padding: 0;
  flex-shrink: 0;
  transition:
    border-color 0.12s,
    color 0.12s;
}
.btn-theme:hover {
  border-color: var(--accent);
  color: var(--accent);
}
.btn-theme:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}
.btn-theme svg {
  width: 1rem;
  height: 1rem;
  display: block;
}
.btn-theme .icon-sun {
  display: none;
}
[data-theme='dark'] .btn-theme .icon-sun {
  display: block;
}
[data-theme='dark'] .btn-theme .icon-moon {
  display: none;
}