:root {
  color-scheme: light dark;
  --border: #d0d0d5;
  --bg-card: rgba(127, 127, 127, 0.06);
  --accent: #3b6fd6;
  --danger: #c0392b;
}

* { box-sizing: border-box; }

body {
  font-family: system-ui, -apple-system, "Segoe UI", sans-serif;
  max-width: 480px;
  margin: 0 auto;
  padding: 1.5rem 1rem;
  line-height: 1.6;
}

header { text-align: center; margin-bottom: 1.5rem; }
h1 { font-size: 1.2rem; margin: 0; }

.status {
  border: 1px solid var(--danger);
  color: var(--danger);
  background: rgba(192, 57, 43, 0.08);
  border-radius: 8px;
  padding: 0.9rem 1rem;
  font-weight: 600;
  text-align: center;
}

.login {
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--bg-card);
  padding: 1.75rem 1.25rem;
}

.login-intro { margin-top: 0; font-size: 0.95rem; }

.login label {
  display: block;
  font-size: 0.85rem;
  margin-bottom: 1rem;
}

.login input {
  display: block;
  width: 100%;
  margin-top: 0.35rem;
  padding: 0.6rem 0.7rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  font: inherit;
  font-size: 1rem;
  background: transparent;
  color: inherit;
}

.login button {
  width: 100%;
  padding: 0.75rem 1rem;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--accent);
  color: white;
  font: inherit;
  font-size: 1rem;
  cursor: pointer;
}

.login button:disabled { opacity: 0.5; cursor: default; }

.login-message {
  margin-top: 1rem;
  margin-bottom: 0;
  font-size: 0.85rem;
  text-align: center;
}

.counter {
  text-align: center;
  font-size: 0.85rem;
  opacity: 0.7;
  margin-bottom: 0.75rem;
}

.card {
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--bg-card);
  padding: 2rem 1.25rem;
  min-height: 40vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 1rem;
  cursor: pointer;
  user-select: none;
}

.card-front { font-size: 1.2rem; font-weight: 600; white-space: pre-wrap; }

.card-back {
  font-size: 1.05rem;
  white-space: pre-wrap;
  border-top: 1px solid var(--border);
  padding-top: 1rem;
}

.hint { text-align: center; font-size: 0.75rem; opacity: 0.55; margin: 0; }

.nav {
  display: flex;
  justify-content: space-between;
  gap: 0.75rem;
  margin-top: 1.25rem;
}

.nav button {
  flex: 1;
  padding: 0.75rem 1rem;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--accent);
  color: white;
  font: inherit;
  font-size: 1rem;
  cursor: pointer;
}

.nav button:disabled { opacity: 0.4; cursor: default; }