body {
  margin: 0;
  font-family: Arial, sans-serif;
  background: #f4f8ff;
  color: #1f2a44;
}

.hub-header {
  text-align: center;
  padding: 30px 20px 10px;
}

.lesson-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 20px;
  padding: 20px;
  max-width: 1100px;
  margin: 0 auto 40px;
}

.lesson-card {
  background: white;
  border-radius: 18px;
  padding: 16px;
  box-shadow: 0 8px 18px rgba(0,0,0,0.08);
  cursor: pointer;
  transition: transform 0.25s ease, box-shadow 0.25s ease;
  text-align: center;
}

.lesson-card:hover {
  transform: translateY(-4px) scale(1.02);
  box-shadow: 0 12px 24px rgba(0,0,0,0.12);
}

.lesson-card img {
  width: 100%;
  max-width: 180px;
  height: 140px;
  object-fit: cover;
  border-radius: 12px;
}

.lesson-card h2 {
  font-size: 1.25rem;
  margin: 12px 0 6px;
}

.lesson-card .main-title {
  font-weight: bold;
  margin: 0 0 6px;
}

.lesson-card .domain {
  font-size: 0.95rem;
  color: #4f6b9a;
}

.lesson-wrapper {
  max-width: 950px;
  margin: 0 auto;
  padding: 20px;
}

.top-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 20px;
}

.score-box,
.progress-box {
  background: white;
  padding: 10px 14px;
  border-radius: 12px;
  box-shadow: 0 6px 14px rgba(0,0,0,0.06);
}

.info-card,
.section-card,
.reward-card {
  background: white;
  border-radius: 18px;
  padding: 22px;
  box-shadow: 0 10px 22px rgba(0,0,0,0.08);
  margin-bottom: 20px;
}

.section-image {
  width: 100%;
  max-width: 240px;
  height: 180px;
  object-fit: cover;
  border-radius: 16px;
  display: block;
  margin: 0 auto 16px;
}

.button-row {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-top: 18px;
}

button {
  border: none;
  border-radius: 999px;
  padding: 12px 18px;
  font-size: 1rem;
  cursor: pointer;
  transition: transform 0.2s ease;
}

button:hover {
  transform: scale(1.03);
}

.primary-btn {
  background: #4c7dff;
  color: white;
}

.secondary-btn {
  background: #edf2ff;
  color: #1f2a44;
}

.choice-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
  gap: 12px;
  margin-top: 18px;
}

.choice-btn {
  background: #fff7e6;
  padding: 16px;
  border-radius: 14px;
  border: 2px solid transparent;
}

.choice-btn.correct {
  border-color: #3dbb6a;
}

.choice-btn.incorrect {
  border-color: #e76f51;
}

.feedback-box {
  margin-top: 16px;
  padding: 14px;
  border-radius: 14px;
  background: #eefaf1;
  font-weight: bold;
}

.standards-list,
.impact-list {
  margin: 8px 0 0 18px;
}

.badge {
  display: inline-block;
  background: #ffe27a;
  padding: 8px 14px;
  border-radius: 999px;
  font-weight: bold;
  margin-top: 12px;
}