:root {
  --primary-color: #2c3e50;
  --secondary-color: #e67e22;
  --light-color: #f8f9fa;
  --dark-color: #343a40;
}

body {
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  color: #333;
  background-color: #f5f5f5;
}

.navbar {
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.navbar-brand {
  font-weight: 700;
  color: var(--primary-color);
}

.highlight {
  color: var(--secondary-color);
}

.course-header {
  background: linear-gradient(rgba(0, 0, 0, 0.8), rgba(0, 0, 0, 0.8)),
    url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" width="1600" height="900" viewBox="0 0 1600 900"><rect width="1600" height="900" fill="%232c3e50"/><polygon fill="%23e67e22" points="957 450 539 900 1396 900"/><polygon fill="%23d35400" points="957 450 872.9 900 1396 900"/><polygon fill="%23e67e22" points="0 0 0 900 1200 900 800 450 0 0"/></svg>');
  background-size: cover;
  background-position: center;
  color: white;
  padding: 60px 0;
}

.sidebar {
  background-color: white;
  border-radius: 10px;
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
  position: sticky;
  top: 100px;
}

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

.module-title {
  background-color: var(--primary-color);
  color: white;
  padding: 15px;
  margin: 0;
  border-radius: 5px;
  font-size: 1.1rem;
  position: relative;
}

.module-number {
  background-color: var(--secondary-color);
  color: white;
  width: 30px;
  height: 30px;
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  margin-right: 10px;
}

.lesson {
  padding: 15px;
  border-bottom: 1px solid #eee;
  display: flex;
  align-items: center;
  transition: all 0.3s;
}

.lesson:hover {
  background-color: #f8f9fa;
}

.lesson-icon {
  margin-right: 15px;
  font-size: 1.2rem;
  color: var(--secondary-color);
}

.lesson-duration {
  color: #6c757d;
  font-size: 0.9rem;
  margin-left: auto;
}

.lesson-completed {
  text-decoration: line-through;
  color: #6c757d;
}

/* .lesson-active {
  background-color: rgba(230, 126, 34, 0.1);
  border-left: 3px solid var(--secondary-color);
} */

.main-content {
  background-color: white;
  border-radius: 10px;
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
  padding: 30px;
}

.lesson-content {
  margin-bottom: 30px;
}

.video-container {
  position: relative;
  padding-bottom: 56.25%;
  height: 0;
  margin-bottom: 20px;
}

.video-placeholder {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: var(--primary-color);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 3rem;
}

.btn-primary {
  background-color: var(--secondary-color);
  border-color: var(--secondary-color);
  padding: 10px 25px;
  font-weight: 600;
}

.btn-primary:hover {
  background-color: #d35400;
  border-color: #d35400;
}

.resources-box {
  background-color: var(--light-color);
  padding: 20px;
  border-radius: 10px;
  margin-bottom: 20px;
}

.resource-item {
  display: flex;
  align-items: center;
  margin-bottom: 10px;
}

.resource-icon {
  color: var(--secondary-color);
  font-size: 1.2rem;
  margin-right: 10px;
}

.quiz-container {
  background-color: var(--light-color);
  padding: 20px;
  border-radius: 10px;
  margin-top: 20px;
}

.quiz-question {
  margin-bottom: 20px;
}

.quiz-option {
  background-color: white;
  padding: 15px;
  border-radius: 5px;
  margin-bottom: 10px;
  cursor: pointer;
  transition: all 0.3s;
  border: 1px solid #dee2e6;
}

.quiz-option:hover {
  border-color: var(--secondary-color);
}

.quiz-option-selected {
  background-color: rgba(230, 126, 34, 0.1);
  border-color: var(--secondary-color);
}

.quiz-option-correct {
  background-color: rgba(40, 167, 69, 0.1);
  border-color: #28a745;
}

.quiz-option-incorrect {
  background-color: rgba(220, 53, 69, 0.1);
  border-color: #dc3545;
}

.instructor-info {
  display: flex;
  margin-bottom: 20px;
}

.instructor-img {
  width: 60px;
  height: 60px;
  border-radius: 50%;
  background-color: var(--secondary-color);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-right: 15px;
  color: white;
  font-size: 1.5rem;
}

.accordion-button:not(.collapsed) {
  background-color: rgba(230, 126, 34, 0.1);
  color: var(--secondary-color);
}

.accordion-button:focus {
  box-shadow: 0 0 0 0.25rem rgba(230, 126, 34, 0.25);
}

.notes-container {
  background-color: var(--light-color);
  border-radius: 10px;
  padding: 20px;
  margin-top: 20px;
}

.completion-badge {
  background-color: #28a745;
  color: white;
  font-size: 0.8rem;
  padding: 3px 8px;
  border-radius: 20px;
  margin-left: 10px;
}

footer {
  background-color: var(--dark-color);
  color: white;
  padding: 50px 0 20px;
  margin-top: 50px;
}

.social-icons a {
  color: white;
  font-size: 1.5rem;
  margin-right: 15px;
}

@media (max-width: 991px) {
  .sidebar {
    position: static;
    margin-bottom: 30px;
  }
}