/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #4a90e2;
    --primary-dark: #357abd;
    --secondary-color: #50c878;
    --text-color: #333;
    --text-light: #666;
    --bg-color: #ffffff;
    --bg-secondary: #f8f9fa;
    --border-color: #e0e0e0;
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 4px 12px rgba(0, 0, 0, 0.15);
    --success-color: #28a745;
    --error-color: #dc3545;
    --warning-color: #ffc107;
}

[data-theme="dark"] {
    --primary-color: #5ba3f5;
    --primary-dark: #4a90e2;
    --secondary-color: #60d888;
    --text-color: #e0e0e0;
    --text-light: #b0b0b0;
    --bg-color: #1a1a1a;
    --bg-secondary: #2d2d2d;
    --border-color: #404040;
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-hover: 0 4px 12px rgba(0, 0, 0, 0.4);
    --success-color: #34ce57;
    --error-color: #ff4757;
    --warning-color: #ffd32a;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-color);
    transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

/* Navigation */
.navbar {
    background-color: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    color: var(--primary-color);
    font-weight: bold;
}

.nav-links {
    display: flex;
    gap: 1.5rem;
    align-items: center;
}

.nav-link {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
    transition: color 0.3s ease;
    cursor: pointer;
}

.nav-link:hover,
.nav-link.active {
    color: var(--primary-color);
}

.theme-toggle {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.5rem;
    transition: transform 0.3s ease;
}

.theme-toggle:hover {
    transform: rotate(20deg);
}

/* Pages */
.page {
    display: none;
    min-height: calc(100vh - 80px);
    padding: 2rem 0;
}

.page.active {
    display: block;
}

/* Hero Section */
.hero {
    text-align: center;
    padding: 4rem 0;
    max-width: 800px;
    margin: 0 auto;
}

.hero-title {
    font-size: 3rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.hero-subtitle {
    font-size: 1.5rem;
    color: var(--text-light);
    margin-bottom: 1.5rem;
}

.hero-description {
    font-size: 1.1rem;
    color: var(--text-light);
    margin-bottom: 2rem;
    line-height: 1.8;
}

/* Buttons */
.btn {
    padding: 0.75rem 2rem;
    font-size: 1rem;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-block;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background-color: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

.btn-secondary {
    background-color: var(--bg-secondary);
    color: var(--text-color);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background-color: var(--border-color);
}

.back-btn {
    margin-bottom: 2rem;
}

/* Features */
.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-top: 4rem;
}

.feature-card {
    background-color: var(--bg-secondary);
    padding: 2rem;
    border-radius: 12px;
    text-align: center;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    border: 1px solid var(--border-color);
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.feature-card h3 {
    margin-bottom: 0.5rem;
    color: var(--primary-color);
}

/* Lessons Grid */
.page-title {
    font-size: 2.5rem;
    margin-bottom: 2rem;
    color: var(--primary-color);
}

.lessons-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
}

.lesson-card {
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1.5rem;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.lesson-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
    border-color: var(--primary-color);
}

.lesson-card.completed::before {
    content: '✓';
    position: absolute;
    top: 1rem;
    right: 1rem;
    background-color: var(--success-color);
    color: white;
    width: 30px;
    height: 30px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
}

.lesson-number {
    font-size: 0.9rem;
    color: var(--text-light);
    margin-bottom: 0.5rem;
}

.lesson-card h3 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.lesson-card p {
    color: var(--text-light);
    font-size: 0.95rem;
}

/* Lesson Content */
.lesson-content {
    max-width: 900px;
    margin: 0 auto;
}

.lesson-section {
    background-color: var(--bg-secondary);
    border-radius: 12px;
    padding: 2rem;
    margin-bottom: 2rem;
    border: 1px solid var(--border-color);
}

.lesson-section h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-size: 1.5rem;
}

.lesson-section p {
    margin-bottom: 1rem;
    line-height: 1.8;
}

.code-example {
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1rem;
    margin: 1rem 0;
    font-family: 'Courier New', monospace;
    overflow-x: auto;
}

.code-example code {
    color: var(--primary-color);
    font-size: 0.95rem;
}

.try-it-btn {
    margin-top: 1rem;
}

/* Code Editor Modal */
.modal {
    display: none;
    position: fixed;
    z-index: 2000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(4px);
}

.modal.active {
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-content {
    background-color: var(--bg-color);
    border-radius: 12px;
    width: 90%;
    max-width: 900px;
    max-height: 90vh;
    overflow-y: auto;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.3);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.modal-header h3 {
    color: var(--primary-color);
    margin: 0;
}

.modal-close {
    background: none;
    border: none;
    font-size: 2rem;
    cursor: pointer;
    color: var(--text-color);
    line-height: 1;
    transition: color 0.3s ease;
}

.modal-close:hover {
    color: var(--error-color);
}

.modal-body {
    padding: 1.5rem;
}

.editor-container {
    margin-bottom: 1rem;
}

#codeEditor {
    width: 100%;
    min-height: 300px;
    padding: 1rem;
    font-family: 'Courier New', monospace;
    font-size: 1rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background-color: var(--bg-secondary);
    color: var(--text-color);
    resize: vertical;
}

.editor-actions {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.output-container {
    margin-top: 1.5rem;
}

.output-container h4 {
    margin-bottom: 0.5rem;
    color: var(--primary-color);
}

.output {
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1rem;
    min-height: 100px;
    font-family: 'Courier New', monospace;
    white-space: pre-wrap;
    word-wrap: break-word;
}

.output.success {
    border-color: var(--success-color);
    background-color: rgba(40, 167, 69, 0.1);
}

.output.error {
    border-color: var(--error-color);
    background-color: rgba(220, 53, 69, 0.1);
}

/* Exercise */
.exercise {
    background-color: var(--bg-secondary);
    border-left: 4px solid var(--primary-color);
    padding: 1.5rem;
    margin: 2rem 0;
    border-radius: 8px;
}

.exercise h4 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.exercise p {
    margin-bottom: 1rem;
}

.exercise-feedback {
    margin-top: 1rem;
    padding: 1rem;
    border-radius: 8px;
    display: none;
}

.exercise-feedback.show {
    display: block;
}

.exercise-feedback.correct {
    background-color: rgba(40, 167, 69, 0.1);
    border: 1px solid var(--success-color);
    color: var(--success-color);
}

.exercise-feedback.incorrect {
    background-color: rgba(220, 53, 69, 0.1);
    border: 1px solid var(--error-color);
    color: var(--error-color);
}

/* Quiz */
.quiz-question {
    margin-bottom: 2rem;
}

.quiz-question h4 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-size: 1.2rem;
}

.quiz-options {
    list-style: none;
}

.quiz-option {
    background-color: var(--bg-secondary);
    border: 2px solid var(--border-color);
    border-radius: 8px;
    padding: 1rem;
    margin-bottom: 0.75rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.quiz-option:hover {
    border-color: var(--primary-color);
    background-color: var(--bg-color);
}

.quiz-option.selected {
    border-color: var(--primary-color);
    background-color: rgba(74, 144, 226, 0.1);
}

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

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

.quiz-actions {
    display: flex;
    gap: 1rem;
    margin-top: 2rem;
}

.quiz-result {
    margin-top: 2rem;
    padding: 1.5rem;
    border-radius: 8px;
    text-align: center;
    display: none;
}

.quiz-result.show {
    display: block;
}

.quiz-result.success {
    background-color: rgba(40, 167, 69, 0.1);
    border: 2px solid var(--success-color);
}

.quiz-result h3 {
    color: var(--success-color);
    margin-bottom: 0.5rem;
}

/* Progress Page */
.progress-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    margin-bottom: 3rem;
}

.stat-card {
    background-color: var(--bg-secondary);
    border-radius: 12px;
    padding: 2rem;
    text-align: center;
    border: 1px solid var(--border-color);
}

.stat-value {
    font-size: 3rem;
    font-weight: bold;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.stat-label {
    color: var(--text-light);
    font-size: 1rem;
}

.progress-bar-container {
    margin-bottom: 3rem;
}

.progress-bar {
    width: 100%;
    height: 30px;
    background-color: var(--bg-secondary);
    border-radius: 15px;
    overflow: hidden;
    border: 1px solid var(--border-color);
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    width: 0%;
    transition: width 0.5s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: bold;
    font-size: 0.9rem;
}

.progress-text {
    text-align: center;
    margin-top: 1rem;
    font-size: 1.2rem;
    color: var(--text-light);
}

.lessons-progress {
    display: grid;
    gap: 1rem;
}

.lesson-progress-item {
    background-color: var(--bg-secondary);
    border-radius: 8px;
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border: 1px solid var(--border-color);
}

.lesson-progress-item.completed {
    border-color: var(--success-color);
}

/* Responsive Design */
@media (max-width: 768px) {
    .hero-title {
        font-size: 2rem;
    }

    .hero-subtitle {
        font-size: 1.2rem;
    }

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

    .nav-links {
        flex-wrap: wrap;
        justify-content: center;
    }

    .container {
        padding: 1rem;
    }

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

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

    .modal-content {
        width: 95%;
        margin: 1rem;
    }
}