:root {
    --primary-color: #4A90E2; /* Couleur bleue principale de l'app */
    --secondary-color: #2c3e50;
    --background-color: #f4f7f9;
    --text-color: #333;
    --white-color: #ffffff;
    --container-width: 1100px;
    --shadow: 0 6px 20px rgba(0,0,0,0.07);
    --border-radius: 12px;
}

*, *::before, *::after {
    box-sizing: border-box;
}

body {
    font-family: 'Poppins', sans-serif;
    line-height: 1.7;
    color: var(--text-color);
    background-color: var(--background-color);
    margin: 0;
    padding-top: 70px;
}

.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 20px;
}

/* --- Header & Navbar --- */
.main-header {
    background-color: var(--white-color);
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
}

.navbar .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
}

.navbar-brand {
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
}

.navbar-nav {
    list-style: none;
    display: flex;
    margin: 0;
    padding: 0;
}

.navbar-nav li {
    margin-left: 30px;
}

.navbar-nav a {
    text-decoration: none;
    color: var(--secondary-color);
    font-weight: 600;
    transition: color 0.3s ease;
}

.navbar-nav a:hover {
    color: var(--primary-color);
}

/* --- Hero Section --- */
.hero {
    background: linear-gradient(45deg, var(--primary-color), #5dade2);
    color: var(--white-color);
    padding: 120px 0;
    text-align: center;
}

.hero h1 {
    font-size: 3.2rem;
    margin-bottom: 15px;
    font-weight: 700;
    line-height: 1.2;
}

.hero p {
    font-size: 1.2rem;
    max-width: 650px;
    margin: 0 auto 30px auto;
    font-weight: 300;
    opacity: 0.9;
}

.btn {
    padding: 14px 30px;
    text-decoration: none;
    border-radius: 8px;
    font-weight: 600;
    transition: all 0.3s ease;
    display: inline-block;
}

.btn-primary {
    background-color: var(--white-color);
    color: var(--primary-color);
    box-shadow: 0 4px 10px rgba(0,0,0,0.1);
}

.btn-primary:hover {
    background-color: #f1f1f1;
    transform: translateY(-3px);
    box-shadow: 0 6px 15px rgba(0,0,0,0.15);
}

/* --- Features Section --- */
.features {
    padding: 100px 0;
    text-align: center;
}

.section-title {
    font-size: 2.8rem;
    color: var(--secondary-color);
    margin-bottom: 60px;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    text-align: left;
}

.feature-card {
    background-color: var(--white-color);
    padding: 35px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
}

.feature-icon {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 15px;
}

.feature-card h3 {
    color: var(--secondary-color);
    margin-top: 0;
    font-size: 1.5rem;
}

/* --- Screenshot Section --- */
.screenshots {
    padding: 100px 0;
    background-color: var(--white-color);
    text-align: center;
}

.screenshot-gallery {
    display: flex;
    justify-content: center;
    gap: 30px;
    margin-top: 40px;
    flex-wrap: wrap;
}

.screenshot-gallery img {
    max-width: 280px;
    border-radius: 15px;
    box-shadow: var(--shadow);
    border: 5px solid var(--white-color);
}

/* --- Generic Page Content --- */
.page-content {
    padding: 80px 0;
    background-color: var(--white-color);
    min-height: 60vh;
}

.page-content .container {
    max-width: 800px;
}

.page-content h1 {
    font-size: 2.8rem;
    color: var(--secondary-color);
    margin-bottom: 30px;
}

.page-content h2 {
    font-size: 1.8rem;
    color: var(--secondary-color);
    margin-top: 40px;
    border-bottom: 2px solid var(--primary-color);
    padding-bottom: 10px;
}

.page-content p, .page-content li {
    font-size: 1.1rem;
    color: #555;
}

/* --- Footer --- */
.main-footer {
    background-color: var(--secondary-color);
    color: var(--white-color);
    padding: 40px 0;
    margin-top: 50px;
}

.main-footer .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.footer-nav {
    list-style: none;
    display: flex;
    margin: 0;
    padding: 0;
}

.footer-nav li {
    margin-left: 20px;
}

.footer-nav a {
    color: var(--white-color);
    text-decoration: none;
    opacity: 0.8;
    transition: opacity 0.3s ease;
}

.footer-nav a:hover {
    opacity: 1;
}

/* --- Responsive Design --- */
@media (max-width: 768px) {
    body {
        padding-top: 60px;
    }
    .navbar .container {
        height: 60px;
    }
    .navbar-brand {
        font-size: 1.5rem;
    }
    .navbar-nav {
        display: none; /* Simple responsive solution: hide nav links */
    }
    .hero {
        padding: 80px 0;
    }
    .hero h1 {
        font-size: 2.2rem;
    }
    .hero p {
        font-size: 1rem;
    }
    .section-title {
        font-size: 2rem;
    }
    .features-grid {
        grid-template-columns: 1fr;
    }
    .main-footer .container {
        flex-direction: column;
        text-align: center;
    }
    .footer-nav {
        margin-top: 15px;
    }
    .footer-nav li {
        margin: 0 10px;
    }
}