body {
  font-family: "Roboto", sans-serif;
  background-color: #f4f4f4;
  margin: 0;
  padding: 0;
}

header {
  background-color: #2c3e50;
  color: white;
  padding: 20px;
  font-size: 24px;
  text-align: center;
  position: relative;
}

.container {
  max-width: 900px;
  margin: auto;
  padding: 20px;
  background: white;
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

h1 {
  text-align: center;
  color: #004080;
}

h3 {
  text-align: center;
  color: #555;
}

.progress-container {
  text-align: center;
  margin-bottom: 20px;
}

.progress {
  height: 12px;
  width: 100%;
  background: #e9ecef;
  border-radius: 5px;
  overflow: hidden;
}

.progress-bar {
  height: 100%;
  background: #28a745;
  width: 0;
  transition: width 0.4s ease-in-out;
}

.progress-text {
  margin-top: 5px;
  font-size: 1rem;
  color: #333;
}

.chapter-list {
  list-style: none;
  padding: 0;
}

.chapter-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: #fff;
  padding: 12px 15px;
  margin-bottom: 8px;
  border-radius: 6px;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
  transition: transform 0.2s;
}

.chapter-item:hover {
  transform: translateY(-3px);
}

.chapter-link {
  text-decoration: none;
  font-size: 16px;
  color: #004080;
  font-weight: 600;
}

.score-display {
  font-size: 14px;
  color: #28a745;
}

.btn {
  padding: 6px 12px;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  font-size: 14px;
  transition: background 0.3s;
}

.btn-primary {
  background: #004080;
  color: white;
}

.btn-primary:hover {
  background: #003366;
}

.btn-success {
  background: #28a745;
  color: white;
}

.btn-success:hover {
  background: #218838;
}

.reset-container {
  text-align: center;
  margin-top: 20px;
}

.reset-btn {
  padding: 8px 15px;
  background: red;
  color: white;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  font-size: 14px;
  transition: background 0.3s;
}

.reset-btn:hover {
  background: darkred;
}