:root {
  --bg: #0f172a;
  --panel: #1e293b;
  --text: #e2e8f0;
  --muted: #94a3b8;
  --accent: #38bdf8;
  --good: #22c55e;
  --bad: #ef4444;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
}

header {
  width: 100%;
  max-width: 640px;
  padding: 1.5rem 1rem 0.5rem;
  display: flex;
  justify-content: space-between;
  align-items: baseline;
}

h1 { font-size: 1.15rem; margin: 0; }

#header-right {
  display: flex;
  align-items: baseline;
  gap: 1rem;
}

#stats { color: var(--muted); font-size: 0.9rem; }

#auth-status { font-size: 0.85rem; }

.auth-link {
  color: var(--accent);
  cursor: pointer;
  background: none;
  border: none;
  font-size: 0.85rem;
  padding: 0;
  font-family: inherit;
}

.auth-link:hover { text-decoration: underline; }

main {
  width: 100%;
  max-width: 640px;
  padding: 1rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

#controls {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--muted);
  font-size: 0.9rem;
}

select {
  background: var(--panel);
  color: var(--text);
  border: 1px solid #334155;
  border-radius: 6px;
  padding: 0.3rem 0.5rem;
}

#deck-position { margin-left: auto; }

.card {
  background: var(--panel);
  border-radius: 12px;
  padding: 2rem 1.5rem;
  min-height: 220px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 1rem;
  cursor: pointer;
  outline: none;
  border: 1px solid #334155;
}

.card:focus { border-color: var(--accent); }

.card-domain {
  color: var(--accent);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.card-question { font-size: 1.15rem; line-height: 1.5; }

.card-answer {
  font-size: 1.05rem;
  color: var(--good);
  border-top: 1px solid #334155;
  padding-top: 1rem;
  line-height: 1.5;
}

.card-explanation {
  font-size: 0.9rem;
  color: var(--muted);
  line-height: 1.5;
}

.hint {
  font-size: 0.75rem;
  color: var(--muted);
  text-align: center;
  margin-top: auto;
}

.hidden { display: none !important; }

.grading {
  display: flex;
  gap: 1rem;
}

.btn {
  flex: 1;
  padding: 0.75rem;
  border-radius: 8px;
  border: none;
  font-size: 1rem;
  cursor: pointer;
  color: white;
}

.btn-correct { background: var(--good); }
.btn-incorrect { background: var(--bad); }