body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  background-color: #12528e;
}

header {
  background-color: #2b3c4e;
  color: white;
  padding: 15px;
  text-align: center;
  border: 2px;
  border-radius: 15px;
  margin: 10px;
}

.container {
  max-width: 800px;
  margin: 10px;
  background: white;
  padding: 20px;
  border-radius: 15px;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
}

.course-overview h2 {
  margin: 0;
}

.course-details {
  margin-top: 10px;
}

.video-list h3,
.video-player h3,
.notes-section h3 {
  margin-bottom: 10px;
}

.video-item {
  padding: 10px;
  border: 1px solid #ddd;
  border-radius: 5px;
  margin-bottom: 10px;
}

.video-player iframe {
  width: 100%;
  height: 315px;
}

button {
  background-color: #28a745;
  color: white;
  border: none;
  padding: 10px 15px;
  cursor: pointer;
  border-radius: 5px;
}

button:hover {
  background-color: #218838;
}

progress {
  width: 100%;
  height: 20px;
}