body {
  font-family: 'Inter', 'Segoe UI', sans-serif;
  background: linear-gradient(135deg, #d0e6ff, #e6f0ff);
  color: #1a1a1a;
  margin: 0;
  padding: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.lessons-container {
  max-width: 760px;
  margin: 32px auto;
  padding: 0 16px;
}

.lesson {
  background: #fff;
  border: 2px solid #1976d2;
  border-radius: 12px;
  padding: 20px 24px;
  margin-bottom: 10px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
  box-shadow: 0 4px 10px rgba(25, 118, 210, 0.2);
  transition: background 0.2s ease, transform 0.2s;
}

.lesson:hover {
  background-color: #ebefff;
  transform: scale(1.01);
}

.lesson h2 {
  font-size: 1.35rem;
  color: #003c8f;
  font-weight: bold;
}

.lesson-number {
  font-size: 1rem;
  color: #0d47a1;
  font-weight: 600;
  margin-top: 4px;
}

.toggle-icon {
  font-size: 1.3rem;
  color: #004ba0;
  font-weight: bold;
  user-select: none;
}

.lesson-content {
display: none;
padding: 20px 28px;
background-color: #f1f5f9;
border-left: 4px solid #0b5ed7;
border-radius: 0 0 12px 12px;
margin-bottom: 24px;
color: #333;
font-size: 1rem;
line-height: 1.6;
}

.lesson-content h3 {
font-size: 1.15rem;
margin-bottom: 8px;
font-weight: 600;
color: #1c3d5a;
}


.connection-line {
font-weight: 600;
color: #0b5ed7;
margin-bottom: 12px;
font-style: italic;
}

.grammar-explain {
margin-bottom: 14px;
white-space: pre-wrap;
}

.grammar-examples {
background: #fff;
padding: 12px 16px;
border: 1px solid #ddd;
border-radius: 8px;
list-style-type: disc;
margin-left: 20px;
color: #444;
font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
}

.grammar-examples li {
margin-bottom: 8px;
}

/* Responsive Design */
@media (max-width: 600px) {
  .lessons-container {
    padding: 12px;
  }

  .lesson {
    padding: 1rem 1rem;
  }

  .lesson h2 {
    font-size: 1rem;
  }

  .lesson-number {
    font-size: 0.9rem;
  }

  .lesson-content {
    padding: 18px 22px;
    font-size: 1rem;
  }

  .lesson-content h3 {
    font-size: 1.05rem;
  }
}