/* Variables CSS */
:root {
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --accent-color: #e74c3c;
    --success-color: #27ae60;
    --warning-color: #f39c12;
    --background-color: #ecf0f1;
    --text-color: #2c3e50;
    --light-gray: #bdc3c7;
    --white: #ffffff;
    --shadow: 0 2px 10px rgba(0,0,0,0.1);
    --border-radius: 8px;
    --transition: all 0.3s ease;
}

/* Reset et styles de base */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--background-color);
}

/* Header */
header {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: var(--white);
    text-align: center;
    padding: 2rem 1rem;
    box-shadow: var(--shadow);
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    font-weight: 300;
}

.subtitle {
    font-size: 1.2rem;
    opacity: 0.9;
    font-weight: 300;
}

/* Barre de progression */
.progress-bar {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    background: var(--white);
    padding: 1rem;
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

.progress-step {
    padding: 0.8rem 1.5rem;
    margin: 0.25rem;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
    background: var(--light-gray);
    color: var(--text-color);
    font-weight: 500;
    min-width: 120px;
    text-align: center;
}

.progress-step.active {
    background: var(--secondary-color);
    color: var(--white);
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

.progress-step:hover:not(.active) {
    background: var(--primary-color);
    color: var(--white);
    transform: translateY(-1px);
}

/* Contenu principal */
main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

.course-section {
    display: none;
    animation: fadeIn 0.5s ease-in-out;
}

.course-section.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.course-section h2 {
    font-size: 2rem;
    margin-bottom: 1.5rem;
    color: var(--primary-color);
    border-bottom: 3px solid var(--secondary-color);
    padding-bottom: 0.5rem;
}

.content {
    background: var(--white);
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    margin-bottom: 2rem;
}

/* Boîtes spéciales */
.highlight-box, .theorem-box, .definition-box, .note-box, .warning-box {
    padding: 1.5rem;
    margin: 1.5rem 0;
    border-radius: var(--border-radius);
    border-left: 4px solid;
}

.highlight-box {
    background: #f8f9fa;
    border-left-color: var(--secondary-color);
}

.theorem-box {
    background: #e8f4fd;
    border-left-color: var(--secondary-color);
}

.theorem-box h3 {
    color: var(--secondary-color);
    margin-bottom: 1rem;
}

.definition-box {
    background: #f0f8ff;
    border-left-color: var(--primary-color);
}

.note-box {
    background: #fff9e6;
    border-left-color: var(--warning-color);
}

.warning-box {
    background: #fdf2f2;
    border-left-color: var(--accent-color);
}

/* Équations */
.equation {
    text-align: center;
    margin: 1.5rem 0;
    padding: 1rem;
    background: #fafafa;
    border-radius: var(--border-radius);
    border: 1px solid #e0e0e0;
}

/* Boutons */
.btn-primary, .btn-secondary, .btn-success, .btn-quiz, .toggle-btn {
    padding: 0.8rem 1.5rem;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    transition: var(--transition);
    text-decoration: none;
    display: inline-block;
    margin: 0.5rem 0.5rem 0.5rem 0;
}

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

.btn-primary:hover {
    background: #2980b9;
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

.btn-secondary {
    background: var(--light-gray);
    color: var(--text-color);
}

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

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

.btn-success:hover {
    background: #229954;
    transform: translateY(-2px);
}

.btn-quiz {
    background: var(--warning-color);
    color: var(--white);
    font-size: 1.1rem;
    padding: 1rem 2rem;
}

.btn-quiz:hover {
    background: #d68910;
}

.toggle-btn {
    background: #ecf0f1;
    color: var(--text-color);
    width: 100%;
    text-align: left;
    margin-bottom: 1rem;
}

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

/* Éléments interactifs */
.interactive-element {
    text-align: center;
    margin: 2rem 0;
    padding: 1rem;
}

.example-toggle {
    margin: 1.5rem 0;
}

.example-content {
    background: #f8f9fa;
    padding: 1.5rem;
    border-radius: var(--border-radius);
    margin-top: 0.5rem;
    border: 1px solid #e9ecef;
}

.example-content.hidden {
    display: none;
}

/* Grille d'exemples */
.example-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
    margin: 2rem 0;
}

.example-card {
    background: var(--white);
    padding: 1.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    cursor: pointer;
    transition: var(--transition);
    border: 2px solid transparent;
}

.example-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 20px rgba(0,0,0,0.15);
    border-color: var(--secondary-color);
}

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

.equation-preview {
    font-family: 'Times New Roman', serif;
    font-size: 1.1rem;
    color: var(--secondary-color);
    margin-top: 0.5rem;
}

.example-details {
    background: var(--white);
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    margin-top: 1.5rem;
}

.example-details.hidden {
    display: none;
}

/* Étapes de démonstration */
.step-by-step {
    margin: 2rem 0;
}

.step {
    background: var(--white);
    padding: 1.5rem;
    margin: 1rem 0;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    border-left: 4px solid var(--secondary-color);
}

.step h4 {
    color: var(--secondary-color);
    margin-bottom: 1rem;
}

/* Liste des applications */
.applications-list {
    list-style: none;
    padding: 0;
}

.applications-list li {
    background: var(--white);
    padding: 1rem;
    margin: 0.5rem 0;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    border-left: 4px solid var(--success-color);
}

.applications-list li strong {
    color: var(--success-color);
}

/* Footer */
footer {
    background: var(--primary-color);
    color: var(--white);
    text-align: center;
    padding: 2rem;
    margin-top: 3rem;
}

.quiz-button {
    margin-top: 1rem;
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.5);
}

.modal.hidden {
    display: none;
}

.modal-content {
    background-color: var(--white);
    margin: 5% auto;
    padding: 2rem;
    border-radius: var(--border-radius);
    width: 90%;
    max-width: 800px;
    max-height: 80vh;
    overflow-y: auto;
    box-shadow: 0 4px 20px rgba(0,0,0,0.3);
}

.close {
    color: var(--light-gray);
    float: right;
    font-size: 2rem;
    font-weight: bold;
    cursor: pointer;
    line-height: 1;
}

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

/* Questions du quiz */
.quiz-question {
    background: var(--white);
    padding: 1.5rem;
    margin: 1rem 0;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

.quiz-question h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.quiz-options {
    list-style: none;
    padding: 0;
}

.quiz-options li {
    padding: 0.5rem;
    margin: 0.5rem 0;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
    background: #f8f9fa;
}

.quiz-options li:hover {
    background: var(--secondary-color);
    color: var(--white);
}

.quiz-options li.selected {
    background: var(--secondary-color);
    color: var(--white);
}

.quiz-options li.correct {
    background: var(--success-color);
    color: var(--white);
}

.quiz-options li.incorrect {
    background: var(--accent-color);
    color: var(--white);
}

/* Responsive Design */
@media (max-width: 768px) {
    header h1 {
        font-size: 2rem;
    }

    .subtitle {
        font-size: 1rem;
    }

    .progress-bar {
        flex-direction: column;
        align-items: center;
    }

    .progress-step {
        width: 90%;
        margin: 0.25rem 0;
    }

    main {
        padding: 1rem;
    }

    .content {
        padding: 1rem;
    }

    .course-section h2 {
        font-size: 1.5rem;
    }

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

    .modal-content {
        margin: 10% auto;
        width: 95%;
        padding: 1rem;
    }
}

@media (max-width: 480px) {
    header {
        padding: 1rem;
    }

    header h1 {
        font-size: 1.5rem;
    }

    .btn-primary, .btn-secondary, .btn-success, .btn-quiz {
        display: block;
        width: 100%;
        margin: 0.5rem 0;
    }

    .interactive-element {
        padding: 0.5rem;
    }
}

/* Animations */
@keyframes slideIn {
    from {
        transform: translateX(-100%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

@keyframes bounce {
    0%, 20%, 53%, 80%, 100% {
        transform: translateY(0);
    }
    40%, 43% {
        transform: translateY(-10px);
    }
    70% {
        transform: translateY(-5px);
    }
    90% {
        transform: translateY(-2px);
    }
}

.bounce {
    animation: bounce 1s ease-in-out;
}

/* États de chargement */
.loading {
    opacity: 0.7;
    pointer-events: none;
}

.loading::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 20px;
    height: 20px;
    margin: -10px 0 0 -10px;
    border: 2px solid var(--secondary-color);
    border-radius: 50%;
    border-top-color: transparent;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

/* Accessibilité */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* Focus pour l'accessibilité */
button:focus,
.progress-step:focus {
    outline: 2px solid var(--secondary-color);
    outline-offset: 2px;
}

/* Impression */
@media print {
    .progress-bar,
    .interactive-element,
    footer {
        display: none;
    }

    .course-section {
        display: block !important;
    }

    body {
        background: white;
        color: black;
    }

    .content {
        box-shadow: none;
        border: 1px solid #ccc;
    }
}