* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: 'Helvetica Neue', Arial, 'Hiragino Kaku Gothic ProN', 'Hiragino Sans', Meiryo, sans-serif;
  background: #f0f4f8;
  min-height: 100vh;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: 16px;
}

.container {
  width: 100%;
  max-width: 480px;
}

header {
  text-align: center;
  margin-bottom: 20px;
}

h1 {
  font-size: 1.6rem;
  color: #1e3a5f;
  margin-bottom: 12px;
}

.stats {
  display: flex;
  justify-content: center;
  gap: 20px;
  background: #fff;
  border-radius: 12px;
  padding: 10px 20px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.08);
  font-size: 0.9rem;
  color: #555;
}

.stats strong {
  color: #3b82f6;
  font-size: 1.1rem;
}

.quiz-card {
  background: #fff;
  border-radius: 16px;
  padding: 28px 24px;
  box-shadow: 0 4px 16px rgba(0,0,0,0.1);
  margin-bottom: 16px;
  min-height: 220px;
}

.category {
  font-size: 0.75rem;
  font-weight: bold;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: #3b82f6;
  background: #eff6ff;
  display: inline-block;
  padding: 3px 10px;
  border-radius: 20px;
  margin-bottom: 16px;
}

.question {
  font-size: 2.4rem;
  font-weight: bold;
  text-align: center;
  color: #1e3a5f;
  letter-spacing: 4px;
  margin: 24px 0;
  line-height: 1.4;
}

.answer-section {
  border-top: 1px solid #e5e7eb;
  padding-top: 16px;
  margin-bottom: 20px;
  animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(-6px); }
  to   { opacity: 1; transform: translateY(0); }
}

.reading {
  font-size: 1.4rem;
  font-weight: bold;
  color: #1e3a5f;
  text-align: center;
  margin-bottom: 8px;
}

.meaning {
  font-size: 0.9rem;
  color: #555;
  text-align: center;
  line-height: 1.6;
}

.btn-group {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.btn {
  flex: 1;
  padding: 12px;
  font-size: 1rem;
  font-weight: bold;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  transition: opacity 0.15s, transform 0.1s;
}

.btn:active {
  transform: scale(0.97);
}

.btn-primary {
  background: #3b82f6;
  color: #fff;
  width: 100%;
}

.btn-primary:hover {
  background: #2563eb;
}

.btn-correct {
  background: #22c55e;
  color: #fff;
}

.btn-correct:hover {
  background: #16a34a;
}

.btn-wrong {
  background: #ef4444;
  color: #fff;
}

.btn-wrong:hover {
  background: #dc2626;
}

.btn-next {
  background: #6b7280;
  color: #fff;
  width: 100%;
  padding: 12px;
  font-size: 1rem;
  font-weight: bold;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  margin-bottom: 12px;
  display: none;
}

.btn-next:hover {
  background: #4b5563;
}

.progress {
  text-align: center;
  font-size: 0.85rem;
  color: #888;
  margin-bottom: 20px;
}

footer {
  text-align: center;
  padding-bottom: 24px;
}

.btn-reset {
  background: transparent;
  color: #9ca3af;
  border: 1px solid #d1d5db;
  padding: 8px 20px;
  font-size: 0.8rem;
  border-radius: 8px;
  cursor: pointer;
  flex: unset;
}

.btn-reset:hover {
  background: #f9fafb;
  color: #6b7280;
}

.hidden {
  display: none !important;
}