/* ==================== Variables ==================== */
:root {
    --primary-blue: #0066cc;
    --dark-blue: #003d99;
    --light-blue: #e6f0ff;
    --accent-blue: #0052a3;
    --dark-text: #1a1a1a;
    --grey-text: #666666;
    --light-grey: #f5f5f5;
    --border-colour: #e0e0e0;
    --white: #ffffff;
    --spacing: 1rem;
    --transition: all 0.3s ease;
}

/* ==================== Reset & Base ==================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    color: var(--dark-text);
    background-color: var(--white);
    line-height: 1.6;
}

/* ==================== Typography ==================== */
h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.2;
}

h1 {
    font-size: 3rem;
    margin-bottom: 0.5rem;
}

h2 {
    font-size: 2.5rem;
    margin-bottom: 2rem;
    color: var(--dark-text);
}

h3 {
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
    color: var(--primary-blue);
}

h4 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
}

p {
    margin-bottom: 1rem;
    color: var(--grey-text);
}

a {
    color: var(--primary-blue);
    text-decoration: none;
    transition: var(--transition);
}

/* ==================== Container ==================== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing);
}

/* ==================== Buttons ==================== */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: 4px;
    font-weight: 600;
    text-decoration: none;
    transition: var(--transition);
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

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

.btn-primary:hover {
    background-color: var(--dark-blue);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 102, 204, 0.3);
}

.btn-secondary {
    background-color: transparent;
    color: var(--primary-blue);
    border: 2px solid var(--primary-blue);
}

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

/* ==================== Navigation ==================== */
.navbar {
    background-color: var(--white);
    border-bottom: 1px solid var(--border-colour);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.nav-wrapper {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
}

.nav-brand {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-blue);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-menu a {
    color: var(--dark-text);
    font-weight: 500;
    transition: var(--transition);
}

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

.nav-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    flex-direction: column;
    gap: 5px;
    padding: 0.5rem;
}

.nav-toggle span {
    width: 25px;
    height: 3px;
    background-color: var(--dark-text);
    border-radius: 2px;
    transition: var(--transition);
}

/* ==================== Hero Section ==================== */
.hero {
    background: linear-gradient(135deg, var(--primary-blue) 0%, var(--dark-blue) 100%);
    color: var(--white);
    padding: 6rem var(--spacing) 6rem;
    text-align: center;
}

.hero-content h1 {
    color: var(--light-grey);
    font-size: 3.5rem;
    margin-bottom: 0.5rem;
}

.subtitle {
    font-size: 1.5rem;
    font-weight: 500;
    margin-bottom: 1.5rem;
    color: var(--light-grey);
}

.hero-description {
    font-size: 1.1rem;
    max-width: 750px;
    margin: 0 auto 2rem;
    color: var(--light-grey);
}

.hero-social {
    display: flex;
    gap: 1.5rem;
    justify-content: center;
    align-items: center;
}

.hero-social-link {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: var(--light-grey);
    color: var(--dark-text);
    font-size: 1.3rem;
    text-decoration: none;
    transition: var(--transition);
    font-weight: 700;
}

.hero-social-link img {
    height: 24px;
    width: 24px;
    object-fit: contain;
}

.hero-social-link:hover {
    background: var(--white);
    transform: translateY(-2px);
}

/* ==================== About Section ==================== */
.about {
    padding: 6rem var(--spacing);
    background-color: var(--light-grey);
}

.about h2 {
    text-align: center;
    color: var(--primary-blue);
}

.about-content {
    max-width: 1000px;
    margin: 0 auto 3rem;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
}

.about-image {
    width: 280px;
    height: 280px;
    border-radius: 50%;
    object-fit: cover;
    box-shadow: 0 4px 20px rgba(0, 102, 204, 0.2);
    justify-self: center;
}

.about-text {
    margin-bottom: 0;
    text-align: left;
    font-size: 1.1rem;
    color: var(--grey-text);
}

.about-text p:last-child {
    margin-bottom: 0;
}

.skills-grid {
    max-width: 1000px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.skill-card {
    background: var(--white);
    padding: 2rem;
    border-radius: 8px;
    border-left: 4px solid var(--primary-blue);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
    transition: var(--transition);
}

.skill-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 16px rgba(0, 102, 204, 0.15);
}

.skill-card h3 {
    margin-bottom: 0.5rem;
    color: var(--dark-text);
}

.skill-card p {
    margin-bottom: 0;
    font-size: 0.95rem;
}

/* ==================== Portfolio Section ==================== */
.portfolio {
    padding-top: 6rem;
}

.portfolio h2 {
    text-align: center;
    color: var(--primary-blue);
}

.portfolio-category {
    margin-top: 3rem;
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 2px solid var(--light-blue);
}

.portfolio-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2rem;
}

.portfolio-item {
    background: var(--white);
    border: 1px solid var(--border-colour);
    border-radius: 8px;
    padding: 2rem;
    transition: var(--transition);
    position: relative;
}

.portfolio-item:hover {
    border-color: var(--primary-blue);
    box-shadow: 0 8px 24px rgba(0, 102, 204, 0.15);
    transform: translateY(-4px);
}

.item-badges {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 0.5rem;
    opacity: 0.7;
    transition: var(--transition);
    margin: 0.5rem auto;
}

.item-badges img {
    width: 22px;
    height: 22px;
    object-fit: contain;
}

.item-header {
    margin-bottom: 0.5rem;
}

.item-header h4 {
    color: var(--dark-text);
    margin: 0;
    font-size: 1.1rem;
    font-weight: 600;
}

.item-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.25rem;
    margin-bottom: 0.75rem;
}

.tag {
    display: inline-block;
    padding: 0.125rem 0.375rem;
    background-color: var(--light-blue);
    color: var(--primary-blue);
    border-radius: 0.25rem;
    font-size: 0.75rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.025em;
}

.portfolio-item p {
    margin-bottom: 1.5rem;
    font-size: 0.95rem;
}

.item-links {
    display: flex;
    gap: 1.5rem;
}

.item-links .link {
    font-weight: 600;
    color: var(--primary-blue);
    border-bottom: 2px solid transparent;
    transition: var(--transition);
}

.item-links .link:hover {
    border-bottom-color: var(--primary-blue);
}

/* ==================== Publications ==================== */
.publications-list {
    display: flex;
    flex-direction: column;
    gap: 2rem;
    margin-bottom: 3rem;
}

.publication-item {
    background: var(--light-grey);
    padding: 2rem;
    border-radius: 8px;
    border-left: 4px solid var(--primary-blue);
    transition: var(--transition);
}

.publication-item:hover {
    background: rgba(230, 240, 255, 0.5);
    transform: translateX(4px);
}

.publication-item h4 {
    color: var(--dark-text);
    margin-bottom: 0.5rem;
}

.publication-meta {
    font-style: italic;
    font-size: 0.9rem;
    color: var(--grey-text);
    margin-bottom: 1rem;
}

.publication-item p:last-of-type {
    margin-bottom: 1rem;
}

/* ==================== Contact Section ==================== */
.contact {
    background: linear-gradient(135deg, var(--light-blue) 0%, rgba(0, 102, 204, 0.05) 100%);
    padding: 6rem var(--spacing);
}

.contact h2 {
    text-align: center;
    color: var(--primary-blue);
}

.contact-intro {
    text-align: center;
    font-size: 1.1rem;
    margin-bottom: 3rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.contact-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    max-width: 900px;
    margin: 0 auto;
}

.contact-info {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.info-item h4 {
    color: var(--dark-text);
    margin-bottom: 0.5rem;
}

.info-item a {
    color: var(--primary-blue);
    font-weight: 500;
}

/* ==================== Form ==================== */
.contact-form {
    background: var(--white);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    color: var(--dark-text);
    font-weight: 600;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-colour);
    border-radius: 4px;
    font-family: inherit;
    font-size: 1rem;
    transition: var(--transition);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-blue);
    box-shadow: 0 0 0 3px rgba(0, 102, 204, 0.1);
}

.contact-form .btn {
    width: 100%;
}

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

.footer p {
    margin-bottom: 0;
    color: rgba(255, 255, 255, 0.8);
}

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

    h2 {
        font-size: 1.75rem;
        margin-bottom: 1.5rem;
    }

    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        flex-direction: column;
        background-color: var(--white);
        padding: 1rem;
        gap: 0.5rem;
        box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
    }

    .nav-menu.active {
        display: flex;
    }

    .nav-social {
        order: 2;
    }

    .nav-toggle {
        display: flex;
        order: 3;
    }

    .hero {
        padding: 4rem var(--spacing) 5rem;
    }

    .hero-content h1 {
        font-size: 2rem;
    }

    .subtitle {
        font-size: 1.1rem;
    }

    .hero-buttons {
        flex-direction: column;
    }

    .hero-buttons .btn {
        width: 100%;
    }

    .about,
    .portfolio,
    .contact {
        padding: 4rem var(--spacing);
    }

    .about-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    .about-image {
        width: 200px;
        height: 200px;
    }

    .about-text {
        text-align: center;
    }

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

    .contact-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

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

@media (max-width: 480px) {
    h1 {
        font-size: 1.5rem;
    }

    h2 {
        font-size: 1.3rem;
    }

    .hero {
        padding: 3rem var(--spacing) 3rem;
    }

    .nav-menu {
        gap: 0;
    }

    .nav-menu a {
        display: block;
        padding: 0.75rem;
    }

    .portfolio-grid {
        gap: 1rem;
    }

    .portfolio-item {
        padding: 1.5rem;
    }

    .about-image {
        width: 150px;
        height: 150px;
    }

    .hero-description {
        font-size: 1rem;
    }
}