.course-detail-page {
  display: flex;
  height: 100vh;
  background-color: #f4f4f4;
  font-family: 'Montserrat', sans-serif;
}

.course-sidebar {
  width: 30%;
  padding: 2rem;
  background-color: white;
  overflow-y: auto;
  border-right: 1px solid #ddd;
}

.course-sidebar h2 {
  font-size: 1.5rem;
  margin-bottom: 2rem;
  color: #2c3e50;
}

.course-section h3 {
  margin-bottom: 1rem;
  font-size: 1rem;
  color: #555;
  border-bottom: 1px solid #eee;
  padding-bottom: 0.5rem;
}

.video-list {
  list-style: none;
  padding: 0;
  margin: 0;
}

.video-item {
  display: flex;
  align-items: center;
  padding: 0.75rem;
  border-radius: 8px;
  cursor: pointer;
  margin-bottom: 0.5rem;
  transition: background 0.3s;
}

.video-item:hover {
  background-color: #f1f1f1;
}

.video-item.active {
  background-color: #e1f5fe;
  border-left: 4px solid #00bcd4;
}

.checkbox {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  border: 2px solid #00bcd4;
  margin-right: 10px;
  position: relative;
}

.checkbox.checked {
  background-color: #00bcd4;
}

.video-icon {
  margin-right: 10px;
  font-size: 1.1rem;
}

.video-title {
  flex-grow: 1;
  font-size: 0.95rem;
}

.video-time {
  font-size: 0.85rem;
  color: #999;
}

/* Right Video Player Area */
.video-area {
  width: 70%;
  padding: 2rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.video-area video {
  width: 100%;
  max-height: 70vh;
  border-radius: 12px;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
  margin-bottom: 1rem;
}

#nextVideoBtn {
  background-color: #00b894;
  color: white;
  padding: 0.75rem 1.5rem;
  border: none;
  border-radius: 8px;
  font-size: 1rem;
  cursor: pointer;
  transition: background 0.3s;
}

#nextVideoBtn:hover {
  background-color: #009f76;
}