.chapter-box {
  background: #f9fbff;
  border-radius: 10px;
  padding: 20px;
  max-width: 600px;
  margin: 20px auto;
  box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}

.chapter-box h2 {
  margin-bottom: 15px;
  font-size: 1.5rem;
  font-weight: bold;
  color: #222;
}

.chapter-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.lesson {
  display: flex;
  align-items: center;
  background: #f0f6ff;
  padding: 10px 15px;
  border-radius: 6px;
  color: #0073e6;
  font-size: 1rem;
  text-decoration: none;
  transition: 0.2s;
}

.lesson:hover {
  background: #e2edff;
}

.lesson-num {
  display: inline-block;
  background: #4da6ff;
  color: #fff;
  font-weight: bold;
  padding: 5px 10px;
  border-radius: 5px;
  margin-right: 10px;
}