:root {
  --color-bg: #f4f5f7;
  --color-card: #ffffff;
  --color-border: #dfe2e8;
  --color-text: #222833;
  --color-muted: #6b7280;
  --color-primary: #2f6fed;
  --color-primary-dark: #1f52b8;
  --color-accent-bg: #eef3ff;
  font-family: 'Segoe UI', 'Malgun Gothic', -apple-system, sans-serif;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.5;
}

.app {
  max-width: 480px;
  margin: 0 auto;
  min-height: 100vh;
  padding: 24px 20px 40px;
  display: flex;
  flex-direction: column;
}

.app-header h1 {
  margin: 0 0 10px;
  font-size: 22px;
  text-align: center;
}

.progress {
  text-align: center;
  font-weight: 600;
  color: var(--color-primary-dark);
  background: var(--color-accent-bg);
  border-radius: 20px;
  padding: 6px 14px;
  width: fit-content;
  margin: 0 auto 24px;
  font-size: 14px;
}

#quiz-view {
  display: flex;
  flex-direction: column;
  align-items: center;
  flex: 1;
}

.card {
  width: 100%;
  height: 260px;
  perspective: 1000px;
  cursor: pointer;
}

.card-inner {
  position: relative;
  width: 100%;
  height: 100%;
  transition: transform 0.5s;
  transform-style: preserve-3d;
}

.card.flipped .card-inner {
  transform: rotateY(180deg);
}

.card-face {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  background: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: 16px;
  box-shadow: 0 4px 14px rgba(0, 0, 0, 0.06);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 24px;
  text-align: center;
}

.card-back {
  transform: rotateY(180deg);
  background: var(--color-accent-bg);
}

.card-label {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.05em;
  color: var(--color-primary);
  text-transform: uppercase;
  margin-bottom: 10px;
}

.card-face p {
  margin: 0;
  font-size: 19px;
  font-weight: 500;
  word-break: keep-all;
}

.hint {
  margin: 14px 0 0;
  font-size: 13px;
  color: var(--color-muted);
}

.actions {
  display: flex;
  gap: 14px;
  width: 100%;
  margin-top: auto;
  padding-top: 32px;
}

.btn {
  flex: 1;
  cursor: pointer;
  font-family: inherit;
  font-size: 16px;
  font-weight: 600;
  border-radius: 12px;
  border: 1px solid var(--color-border);
  padding: 16px;
  min-height: 52px;
}

.btn.primary {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: #fff;
}
.btn.primary:active { background: var(--color-primary-dark); }

.btn.secondary {
  background: #fff;
  color: var(--color-muted);
}
.btn.secondary:active { background: #f0f2f6; }

.done-view {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
}

.done-view.hidden {
  display: none;
}

.done-emoji {
  font-size: 56px;
  margin: 0 0 8px;
}

.done-view h2 {
  margin: 0 0 6px;
}

.done-view p {
  color: var(--color-muted);
  margin: 0;
}