:root {
    --primary-color: #0d2c4b;
    --secondary-color: #1a5a96;
    --accent-color: #4f8dc8;
    --light-gray: #f4f7f6;
    --dark-gray: #333;
    --white-color: #ffffff;
    --font-family: 'Poppins', sans-serif;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    line-height: 1.7;
    color: var(--dark-gray);
    background-color: var(--white-color);
}

header {
    background-color: var(--white-color);
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    width: 100%;
    z-index: 1000;
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 5%;
    max-width: 1400px;
    margin: 0 auto;
}

.nav-logo {
    color: var(--primary-color);
    font-weight: 700;
    font-size: 1.2rem;
    text-decoration: none;
}

.nav-links {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
}

.nav-links li {
    padding: 0 1rem;
}

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

.nav-links a:hover {
    color: var(--accent-color);
}

.hamburger {
    display: none;
    cursor: pointer;
}

.hamburger .bar {
    display: block;
    width: 25px;
    height: 3px;
    margin: 5px auto;
    background-color: var(--primary-color);
    transition: all 0.3s ease-in-out;
}

#hero {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 4rem 5%;
    min-height: 90vh;
    flex-wrap: wrap-reverse;
    gap: 2rem;
    color: var(--white-color);
    /* --- UPDATED TO USE THE NEW, WEBSAFE FILENAME --- */
    background-image: linear-gradient(rgba(13, 44, 75, 0.6), rgba(13, 44, 75, 0.6)), url('africa-dev.jpg');
    background-size: cover;
    background-position: center;
}

.hero-content {
    flex: 1;
    max-width: 600px;
    z-index: 1;
}

.hero-title {
    font-size: 2.8rem;
    color: var(--white-color);
    font-weight: 700;
    line-height: 1.2;
}

.hero-subtitle {
    font-size: 1.2rem;
    color: rgba(255, 255, 255, 0.9);
    margin: 1rem 0 2rem;
}

.hero-image {
    flex: 1;
    max-width: 400px;
    text-align: center;
    z-index: 1;
}

.hero-image img {
    width: 100%;
    max-width: 350px;
    height: auto;
    border-radius: 50%;
    border: 8px solid var(--white-color);
    box-shadow: 0 10px 30px rgba(0,0,0,0.15);
}

.content-section {
    padding: 4rem 5%;
    max-width: 1200px;
    margin: 0 auto;
}

.section-title {
    text-align: center;
    font-size: 2.2rem;
    color: var(--primary-color);
    margin-bottom: 3rem;
    font-weight: 700;
}
.section-subtitle {
    text-align: center;
    max-width: 800px;
    margin: -2rem auto 2rem;
    font-size: 1.1rem;
}
.btn {
    display: inline-block;
    background: var(--accent-color);
    color: var(--white-color);
    padding: 12px 28px;
    border-radius: 5px;
    text-decoration: none;
    font-weight: 600;
    transition: background-color 0.3s ease, transform 0.3s ease;
}

.btn:hover {
    background: var(--secondary-color);
    transform: translateY(-3px);
}

#about p {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
    font-size: 1.1rem;
}

.competencies-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1rem;
}

.competency-item {
    background: var(--light-gray);
    padding: 1.5rem;
    border-radius: 8px;
    text-align: center;
    font-weight: 600;
    color: var(--secondary-color);
    border-left: 5px solid var(--accent-color);
}

.timeline {
    position: relative;
    max-width: 800px;
    margin: 0 auto;
}
.timeline::after {
    content: '';
    position: absolute;
    width: 4px;
    background-color: var(--light-gray);
    top: 0;
    bottom: 0;
    left: 20px;
    margin-left: -2px;
}
.timeline-item {
    padding: 1rem 0 2rem 60px;
    position: relative;
}
.timeline-dot {
    content: '';
    position: absolute;
    width: 20px;
    height: 20px;
    background-color: var(--white-color);
    border: 4px solid var(--secondary-color);
    border-radius: 50%;
    left: 20px;
    margin-left: -10px;
    z-index: 1;
}
.timeline-content h3 {
    font-size: 1.3rem;
    color: var(--primary-color);
}
.timeline-company {
    font-style: italic;
    color: var(--dark-gray);
    margin-bottom: 0.5rem;
}

.video-container {
    position: relative;
    padding-bottom: 56.25%; /* 16:9 aspect ratio */
    height: 0;
    overflow: hidden;
    max-width: 100%;
    background: #000;
    border-radius: 8px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.15);
    margin: 0 auto 2rem;
}
.video-container iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}
.project-links {
    text-align: center;
}

#publications {
    background-color: var(--light-gray);
}
.publications-container {
    display: grid;
    gap: 2rem;
    max-width: 900px;
    margin: 0 auto;
}
.publication-card {
    background: var(--white-color);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.07);
    border-left: 5px solid var(--primary-color);
}
.publication-card h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-size: 1.25rem;
}
.publication-links {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}
.link-btn {
    display: inline-flex; 
    align-items: center; 
    gap: 8px;
    background: var(--secondary-color);
    color: var(--white-color);
    padding: 8px 16px;
    border-radius: 5px;
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 600;
    transition: background-color 0.3s ease;
}
.link-btn:hover {
    background: var(--primary-color);
}

#contact {
    background-color: var(--white-color);
    text-align: center;
}

.contact-container p {
    max-width: 600px;
    margin: 0 auto 2rem;
    font-size: 1.1rem;
}

.contact-details {
    margin-top: 2rem;
}

.contact-details p {
    margin-bottom: 0.5rem;
}

.contact-details a {
    color: var(--secondary-color);
    text-decoration: none;
    font-weight: 600;
}
.contact-details a:hover {
    text-decoration: underline;
}

footer {
    background: var(--primary-color);
    color: var(--light-gray);
    text-align: center;
    padding: 1.5rem 5%;
}

/* Responsive Styles */
@media (max-width: 768px) {
    .nav-links {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: var(--white-color);
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: 0 10px 27px rgba(0, 0, 0, 0.05);
    }
    .nav-links.active {
        left: 0;
    }
    .nav-links li {
        padding: 1.5rem 0;
    }
    .hamburger {
        display: block;
    }
    .hamburger.active .bar:nth-child(2) {
        opacity: 0;
    }
    .hamburger.active .bar:nth-child(1) {
        transform: translateY(8px) rotate(45deg);
    }
    .hamburger.active .bar:nth-child(3) {
        transform: translateY(-8px) rotate(-45deg);
    }
    
    #hero {
        padding: 2rem 5%;
        text-align: center;
    }
    .hero-content {
        order: 2;
        flex-basis: 100%;
    }
    .hero-image {
        order: 1;
        margin-bottom: 2rem;
        flex-basis: 100%;
    }
    .hero-title {
        font-size: 2.2rem;
    }
}