:root {
  --bg: #0f172a;
  --card: #1e293b;
  --accent: #38bdf8;
  --accent-hover: #0284c7;
  --fg: #f8fafc;
  --muted: #94a3b8;
  --correct: #22c55e;
  --incorrect: #ef4444;
  --border: #334155;
  --font-scale: 1;
}
:root[data-theme="light"] {
  --bg: #f8fafc;
  --card: #ffffff;
  --accent: #0284c7;
  --accent-hover: #0369a1;
  --fg: #0f172a;
  --muted: #64748b;
  --correct: #16a34a;
  --incorrect: #dc2626;
  --border: #cbd5e1;
}
@media (prefers-color-scheme: light) {
  :root:not([data-theme="dark"]) {
    --bg: #f8fafc; --card: #ffffff; --accent: #0284c7; --accent-hover: #0369a1;
    --fg: #0f172a; --muted: #64748b; --correct: #16a34a; --incorrect: #dc2626; --border: #cbd5e1;
  }
}

* { box-sizing: border-box; }
html { font-size: calc(16px * var(--font-scale)); }
body {
  margin: 0; background: var(--bg); color: var(--fg); min-height: 100vh;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  transition: background-color 0.2s, color 0.2s;
  display: flex; justify-content: center; padding: 1rem;
}
#app {
  width: 100%; max-width: 960px; background: var(--card); border: 1px solid var(--border);
  border-radius: 20px; padding: 1.5rem; margin: 1rem 0;
  box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.15);
  display: flex; flex-direction: column; gap: 1rem;
}

h1, h2, h3 { line-height: 1.25; margin: 0; }
.muted { color: var(--muted); }

.top-controls {
  display: flex; justify-content: space-between; align-items: center;
  border-bottom: 1px solid var(--border); padding-bottom: 0.75rem;
}
.control-group { display: flex; gap: 0.5rem; align-items: center; }

nav.tabs { display: flex; gap: 1rem; }
nav.tabs a { color: var(--muted); text-decoration: none; padding: 0.3rem 0.1rem; }
nav.tabs a[aria-current="page"] { color: var(--fg); border-bottom: 2px solid var(--accent); }

table { width: 100%; border-collapse: collapse; background: color-mix(in srgb, var(--fg) 2%, transparent); border-radius: 10px; overflow: hidden; }
th, td { text-align: left; padding: 0.5rem 0.75rem; border-bottom: 1px solid var(--border); font-size: 0.9rem; }
th { color: var(--muted); font-weight: 600; font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.03em; }

.card {
  background: color-mix(in srgb, var(--fg) 2%, transparent); border: 1px solid var(--border);
  border-radius: 12px; padding: 1.1rem;
}

button, .btn {
  cursor: pointer; border: 1px solid var(--border); background: var(--card); color: var(--fg);
  border-radius: 8px; padding: 0.5rem 0.9rem; font-size: 0.9rem; font-family: inherit;
}
.btn-primary { background: var(--accent); border-color: var(--accent); color: #0f172a; font-weight: 600; }
.btn-secondary { background: var(--border); color: var(--fg); border-color: var(--border); }
.btn-sm { padding: 0.4rem 0.6rem; font-size: 0.8rem; }
button:hover, .btn:hover { filter: brightness(1.1); }

input, select {
  padding: 0.45rem 0.6rem; border-radius: 6px; border: 1px solid var(--border);
  background: var(--bg); color: var(--fg); font-family: inherit;
}

.badge { font-size: 0.75rem; padding: 0.1rem 0.5rem; border-radius: 999px; background: var(--border); color: var(--muted); }
.badge.revoked { background: color-mix(in srgb, var(--incorrect) 20%, var(--card)); color: var(--incorrect); }
.badge.unused { background: color-mix(in srgb, var(--accent) 20%, var(--card)); color: var(--accent); }
.badge.redeemed { background: color-mix(in srgb, var(--correct) 20%, var(--card)); color: var(--correct); }

.generate-form { display: flex; gap: 0.5rem; align-items: center; flex-wrap: wrap; }
.expires-input { width: 11rem; }
.hidden-file-input { display: none; }