:root {
    --primary: #6e48aa;
    --secondary: #9d50bb;
    --accent: #4776E6;
    --dark: #1a1a2e;
    --light: #f8f9fa;
    --tech-gradient: linear-gradient(135deg, var(--primary), var(--secondary));
}

body {
    font-family: 'Poppins', sans-serif;
    line-height: 1.7;
    color: #2d3748;
    background-color: #f5f7fa;
}

header {
    background: linear-gradient(135deg, #1E3A8A, #3B82F6); /* Dégradé de bleu */
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    position: relative;
    overflow: hidden;
    color: #FFFFFF; /* Texte blanc */
}

header::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, #1D4ED8, #60A5FA); /* Dégradé de bleu clair */
}
.nav-link {
    padding: 0.75rem 1.25rem;
    font-weight: 500;
    position: relative;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    width: 0;
    height: 3px;
    background: white;
    transition: all 0.3s ease;
    transform: translateX(-50%);
}

.nav-link:hover::after {
    width: 70%;
}

.card {
    border: none;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(0,0,0,0.05);
    transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    background: white;
}

.card:hover {
    transform: translateY(-8px);
    box-shadow: 0 15px 30px rgba(110, 72, 170, 0.15);
}

.card-body {
    padding: 1.5rem;
}

.badge {
    font-weight: 600;
    letter-spacing: 0.8px;
    padding: 0.35em 0.65em;
}

.btn-outline-primary {
    border-width: 2px;
    font-weight: 600;
    letter-spacing: 0.5px;
}

.hero {
    background: url('../../img/deep.jpg') center/cover;
    padding: 3rem 0;
    position: relative;
    color: white;
    margin-bottom: 2rem;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(30, 30, 46, 0.7);
}

.hero h2 {
    font-size: 2.5rem;
    text-shadow: 0 2px 4px rgba(0,0,0,0.3);
}

.hero p.lead {
    font-size: 1.25rem;
    text-shadow: 0 1px 2px rgba(0,0,0,0.2);
}

@media (max-width: 768px) {
    header {
        text-align: center;
    }
    .nav {
        justify-content: center !important;
    }
    .hero {
        padding: 3rem 0;
    }
}

/* Tech elements */
.tech-icon {
    width: 60px;
    height: 60px;
    background: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    margin: 0 auto 1rem;
}

.tech-icon i {
    font-size: 1.75rem;
    color: var(--primary);
}

/* Animation */
@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

.floating {
    animation: float 6s ease-in-out infinite;
}

/* Research Header with Background Image */
.research-header {
    background: url('../../img/ia_brain.jpg') center/cover no-repeat;
    padding: 3rem 0;
    position: relative;
    border-radius: 12px;
    margin-bottom: 2rem;
    color: white;
}

.research-header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(30, 58, 138, 0.8); /* Dark blue overlay */
    border-radius: 12px;
    z-index: 0;
}

.research-header h2, 
.research-header p {
    position: relative;
    z-index: 1;
}

.research-header p {
    color: rgba(255, 255, 255, 0.9) !important;
}

/* About Research Section with Background Image */
.about-research {
    background: url('../../img/deep.jpg') center/cover no-repeat;
    padding: 3rem;
    position: relative;
    border-radius: 12px;
    color: white;
}

.about-research::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(30, 58, 138, 0.7); /* Dark blue overlay */
    border-radius: 12px;
    z-index: 0;
}

.about-research h3,
.about-research p {
    position: relative;
    z-index: 1;
}