* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background: #1a1a1a;
    color: #e0e0e0;
    min-height: 100vh;
    display: flex;
}

.learning-container {
    display: flex;
    width: 100%;
}

/* Sidebar Styles */
.sidebar {
    width: 280px;
    background: #2d2d2d;
    padding: 2rem;
    height: 100vh;
    position: fixed;
}

.sidebar h2 {
    color: #3498db;
    margin-bottom: 2rem;
    font-size: 1.5rem;
}

.class-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.class-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s ease;
    background: #363636;
}

.class-item:hover {
    background: #404040;
    transform: translateX(5px);
}

.class-item.active {
    background: #3498db;
    color: white;
}

.class-item i {
    font-size: 1.2rem;
}

/* Main Content Styles */
.main {
    flex: 1;
    margin-left: 280px;
    padding: 2rem;
}

.header {
    margin-bottom: 2rem;
}

.header h1 {
    color: #3498db;
    margin-bottom: 1.5rem;
}

.tabs {
    display: flex;
    gap: 1rem;
    border-bottom: 2px solid #3d3d3d;
    padding-bottom: 1rem;
}

.tab {
    background: none;
    border: none;
    color: #888;
    cursor: pointer;
    padding: 0.5rem 1rem;
    font-size: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: color 0.3s ease;
}

.tab:hover {
    color: #3498db;
}

.tab.active {
    color: #3498db;
}

/* Content Styles */
.content {
    display: none;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
    padding: 1rem 0;
}

.content.active {
    display: grid;
}

.card {
    background: #2d2d2d;
    border-radius: 12px;
    overflow: hidden;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.3);
}

.card-content {
    padding: 1.5rem;
}

.icon {
    font-size: 2rem;
    color: #3498db;
    margin-bottom: 1rem;
}

.card h3 {
    margin-bottom: 0.5rem;
    color: #fff;
}

.card p {
    color: #888;
    margin-bottom: 1.5rem;
    line-height: 1.5;
}

.quiz-info {
    display: flex;
    gap: 1rem;
    margin: 1rem 0;
    font-size: 0.9rem;
    color: #888;
}

.btn-primary {
    width: 100%;
    padding: 0.8rem;
    background: #3498db;
    color: white;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.btn-primary:hover {
    background: #2980b9;
    box-shadow: 0 4px 12px rgba(52, 152, 219, 0.3);
}

/* Quiz Specific Styles */
.quiz-container {
    max-width: 800px;
    margin: 2rem auto;
    padding: 2rem;
    background: #2d2d2d;
    border-radius: 12px;
}

.quiz-header {
    text-align: center;
    margin-bottom: 2rem;
}

.quiz-progress {
    color: #888;
    font-size: 0.9rem;
    margin-top: 1rem;
}

.question-text {
    font-size: 1.2rem;
    margin-bottom: 1.5rem;
}

.options-container {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.option-button {
    padding: 1rem;
    background: #363636;
    border: none;
    border-radius: 6px;
    color: #e0e0e0;
    cursor: pointer;
    transition: all 0.3s ease;
    text-align: left;
}

.option-button:hover {
    background: #404040;
}

.option-button.selected {
    background: #3498db;
    color: white;
}

.feedback-container {
    margin: 1rem 0;
    padding: 1rem;
    border-radius: 6px;
    background: rgba(52, 152, 219, 0.1);
}

/* Lesson Specific Styles */
.lesson-container {
    max-width: 800px;
    margin: 2rem auto;
    padding: 2rem;
}

.content-block {
    margin-bottom: 2rem;
    line-height: 1.6;
}

.content-block.markdown h1,
.content-block.markdown h2,
.content-block.markdown h3 {
    color: #3498db;
    margin: 1.5rem 0 1rem;
}

.content-block.markdown ul,
.content-block.markdown ol {
    padding-left: 2rem;
    margin: 1rem 0;
}

.content-block.code {
    background: #363636;
    padding: 1rem;
    border-radius: 6px;
    font-family: monospace;
}

.content-block img {
    max-width: 100%;
    border-radius: 6px;
    margin: 1rem 0;
}

/* Responsive Design */
@media (max-width: 768px) {
    .sidebar {
        width: 100%;
        height: auto;
        position: static;
    }

    .main {
        margin-left: 0;
    }

    .learning-container {
        flex-direction: column;
    }

    .content {
        grid-template-columns: 1fr;
    }
}

/* Add these styles to your existing CSS */

.page-container {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 4rem 2rem 2rem;
    background: #1a1a1a;
}

.back-link {
    position: fixed;
    top: 2rem;
    left: 2rem;
    color: #3498db;
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1rem;
    z-index: 100;
    padding: 0.5rem 1rem;
    background: rgba(45, 45, 45, 0.9);
    border-radius: 6px;
    transition: all 0.3s ease;
}

.back-link:hover {
    background: #3498db;
    color: white;
}

.quiz-container {
    width: 100%;
    max-width: 600px;
    background: #2d2d2d;
    border-radius: 12px;
    padding: 2rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.lesson-container {
    width: 100%;
    max-width: 800px;
    background: #2d2d2d;
    border-radius: 12px;
    padding: 2rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.page-title {
    font-size: 2rem;
    color: #fff;
    margin-bottom: 2rem;
    text-align: center;
}

.quiz-progress {
    text-align: center;
    color: #888;
    margin-bottom: 2rem;
    font-size: 0.9rem;
}

.quiz-content {
    margin-bottom: 2rem;
}

.question-text {
    font-size: 1.2rem;
    color: #fff;
    margin-bottom: 1.5rem;
    text-align: center;
}

.options-container {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.option-button {
    width: 100%;
    padding: 1rem;
    background: #363636;
    border: 2px solid transparent;
    border-radius: 6px;
    color: #fff;
    cursor: pointer;
    transition: all 0.2s ease;
    text-align: left;
}

.option-button:hover {
    background: #404040;
    border-color: #3498db;
}

.option-button.selected {
    background: #3498db;
    color: white;
    border-color: #2980b9;
}

.quiz-actions {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.lesson-body {
    color: #e0e0e0;
    line-height: 1.6;
}

.content-block {
    margin-bottom: 2rem;
    background: #363636;
    padding: 1.5rem;
    border-radius: 8px;
}

.content-block:last-child {
    margin-bottom: 0;
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .page-container {
        padding: 5rem 1rem 1rem;
    }

    .back-link {
        top: 1rem;
        left: 1rem;
    }

    .quiz-container,
    .lesson-container {
        padding: 1.5rem;
    }
}