* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: linear-gradient(135deg, #dbeafe, #f8fafc);
  color: #111827;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 24px;
}

.app {
  width: 100%;
  max-width: 680px;
}

.card {
  background: white;
  border-radius: 24px;
  padding: 36px;
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.12);
}

.hidden {
  display: none;
}

.tag {
  display: inline-block;
  background: #eff6ff;
  color: #2563eb;
  padding: 8px 14px;
  border-radius: 999px;
  font-weight: 700;
  font-size: 14px;
}

h1 {
  font-size: 36px;
  margin: 18px 0 12px;
}

h2 {
  font-size: 24px;
}

p {
  font-size: 18px;
  line-height: 1.7;
}

button {
  width: 100%;
  border: none;
  border-radius: 14px;
  padding: 16px 20px;
  margin-top: 16px;
  font-size: 17px;
  font-weight: 700;
  cursor: pointer;
  background: #2563eb;
  color: white;
}

button:hover {
  background: #1d4ed8;
}

.choice {
  background: #f3f4f6;
  color: #111827;
  text-align: left;
}

.choice:hover {
  background: #e5e7eb;
}

.top {
  display: flex;
  justify-content: space-between;
  font-weight: 700;
  color: #4b5563;
}

.progress {
  height: 12px;
  background: #e5e7eb;
  border-radius: 999px;
  overflow: hidden;
  margin: 18px 0 28px;
}

#progress-bar {
  height: 100%;
  width: 0%;
  background: #2563eb;
  transition: 0.3s;
}

.review-item {
  background: #f9fafb;
  padding: 16px;
  border-radius: 14px;
  margin: 12px 0;
  border-left: 6px solid #d1d5db;
}

.review-item.correct {
  border-left-color: #22c55e;
}

.review-item.wrong {
  border-left-color: #ef4444;
}

.correct-text {
  color: #16a34a;
  font-weight: 800;
}

.wrong-text {
  color: #dc2626;
  font-weight: 800;
}

@media (max-width: 520px) {
  .card {
    padding: 24px;
  }

  h1 {
    font-size: 28px;
  }
}