/* ============================================
   MINIMALIST ACADEMIC PORTFOLIO STYLES
   Color Palette: #333 (Black), #FFF (White), #F5F5F5 (Light Grey)
   ============================================ */

/* Reset & Base Styles */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', 'Roboto', 'Helvetica Neue', -apple-system, BlinkMacSystemFont, sans-serif;
    font-size: 16px;
    line-height: 1.8;
    letter-spacing: 0.02em;
    color: #333;
    background-color: #FFF;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

a {
    color: #333;
    text-decoration: none;
    transition: color 0.3s ease;
}

a:hover {
    color: #666;
}

/* ============================================
   NAVIGATION
   ============================================ */

.nav-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background-color: #FFF;
    border-bottom: 1px solid #F5F5F5;
    z-index: 1000;
    padding: 1.5rem 0;
    transition: box-shadow 0.3s ease;
}

.nav-header.scrolled {
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
}

.main-nav {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: center;
    gap: 3rem;
    flex-wrap: wrap;
}

.nav-link {
    font-size: 0.95rem;
    font-weight: 400;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: #333;
    padding: 0.5rem 0;
    position: relative;
    transition: color 0.3s ease;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 1px;
    background-color: #333;
    transition: width 0.3s ease;
}

.nav-link:hover::after {
    width: 100%;
}

/* ============================================
   HERO SECTION
   ============================================ */

.hero-section {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 8rem 2rem 4rem;
    background-color: #FFF;
}

.hero-content {
    max-width: 900px;
    text-align: center;
    margin: 0 auto;
}

.hero-image {
    width: 250px;
    height: 250px;
    border-radius: 50%;
    object-fit: cover;
    object-position: center 20%;
    margin: 0 auto 2.5rem;
    display: block;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.12);
}

.hero-headline {
    font-size: clamp(2rem, 5vw, 3.5rem);
    font-weight: 700;
    line-height: 1.3;
    letter-spacing: -0.02em;
    color: #333;
    margin-bottom: 2rem;
}

.hero-subheadline {
    font-size: clamp(1.1rem, 2vw, 1.5rem);
    font-weight: 400;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: #666;
    margin-bottom: 1rem;
}

.hero-description {
    font-size: 1.1rem;
    font-weight: 300;
    color: #666;
    margin-bottom: 3rem;
}

.hero-bio {
    font-size: 1.1rem;
    line-height: 1.9;
    color: #333;
    max-width: 700px;
    margin: 0 auto 2rem;
    font-weight: 300;
}

.hero-link {
    margin-top: 2rem;
}

.hero-link a {
    font-size: 0.95rem;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    border-bottom: 1px solid #333;
    padding-bottom: 2px;
    transition: border-color 0.3s ease;
}

.hero-link a:hover {
    border-bottom-color: #666;
}

/* ============================================
   SECTION STYLES
   ============================================ */

section {
    padding: 6rem 0;
}

.section-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

.section-title {
    font-size: clamp(2rem, 4vw, 3rem);
    font-weight: 300;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: #333;
    margin-bottom: 4rem;
    text-align: center;
    position: relative;
    padding-bottom: 1.5rem;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 1px;
    background-color: #333;
}

/* ============================================
   RESEARCH SECTION
   ============================================ */

.research-section {
    background-color: #F5F5F5;
}

.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2.5rem;
    margin-top: 3rem;
}

.research-card {
    background-color: #FFF;
    padding: 2.5rem;
    border: 1px solid transparent;
    transition: all 0.3s ease;
    display: flex;
    flex-direction: column;
}

.research-card:hover {
    border-color: #E0E0E0;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.05);
}

.card-title {
    font-size: 1.3rem;
    font-weight: 500;
    line-height: 1.5;
    margin-bottom: 1.5rem;
    color: #333;
}

.card-title a {
    color: #333;
    transition: color 0.3s ease;
}

.card-title a:hover {
    color: #666;
}

.card-publication {
    font-size: 0.9rem;
    font-style: italic;
    color: #555;
    margin-bottom: 1rem;
    line-height: 1.6;
    font-weight: 300;
}

.card-summary {
    font-size: 1rem;
    line-height: 1.8;
    color: #666;
    margin-bottom: 1.5rem;
    flex-grow: 1;
    font-weight: 300;
}

.read-more-btn {
    background-color: transparent;
    border: 1px solid #333;
    color: #333;
    padding: 0.75rem 2rem;
    font-size: 0.9rem;
    font-weight: 400;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    cursor: pointer;
    transition: all 0.3s ease;
    align-self: flex-start;
    margin-top: auto;
    font-family: inherit;
}

.read-more-btn:hover {
    background-color: #333;
    color: #FFF;
}

.card-expanded {
    display: none;
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 1px solid #F5F5F5;
    animation: fadeIn 0.4s ease;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.card-expanded p {
    font-size: 1rem;
    line-height: 1.9;
    color: #333;
    margin-bottom: 1.5rem;
    font-weight: 300;
}

.card-expanded strong {
    font-weight: 600;
    color: #333;
}

.card-image {
    margin: 2rem 0;
}

.card-image img {
    width: 100%;
    height: auto;
    margin-bottom: 1rem;
}

.card-image figcaption {
    font-size: 0.9rem;
    color: #666;
    font-style: italic;
    text-align: center;
    margin-top: 0.5rem;
}

.card-citation {
    margin-top: 2rem;
    padding-top: 1.5rem;
    border-top: 1px solid #F5F5F5;
}

.card-citation a {
    font-size: 0.95rem;
    color: #333;
    line-height: 1.8;
    text-decoration: underline;
    text-decoration-thickness: 1px;
    text-underline-offset: 3px;
}

.card-citation a:hover {
    color: #666;
}

/* ============================================
   CV SECTION
   ============================================ */

.cv-section {
    background-color: #FFF;
}

.cv-content {
    text-align: center;
    padding: 2rem 0;
}

.cv-content p {
    font-size: 1.1rem;
    color: #666;
    margin-bottom: 2rem;
    font-weight: 300;
}

.cv-download-btn {
    display: inline-block;
    border: 1px solid #333;
    padding: 1rem 3rem;
    font-size: 0.95rem;
    font-weight: 400;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: #333;
    transition: all 0.3s ease;
}

.cv-download-btn:hover {
    background-color: #333;
    color: #FFF;
}

/* ============================================
   CONTACT SECTION
   ============================================ */

.contact-section {
    background-color: #F5F5F5;
}

.contact-content {
    text-align: center;
    padding: 2rem 0;
}

.contact-content p {
    font-size: 1.1rem;
    color: #666;
    margin-bottom: 1rem;
    font-weight: 300;
}

.contact-content a {
    color: #333;
    border-bottom: 1px solid #333;
    padding-bottom: 2px;
    transition: border-color 0.3s ease;
}

.contact-content a:hover {
    border-bottom-color: #666;
}

/* ============================================
   FOOTER
   ============================================ */

.main-footer {
    background-color: #333;
    color: #FFF;
    text-align: center;
    padding: 3rem 2rem;
}

.main-footer p {
    font-size: 0.9rem;
    font-weight: 300;
    letter-spacing: 0.05em;
    color: #CCC;
}

/* ============================================
   BACK TO TOP BUTTON
   ============================================ */

.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 50px;
    height: 50px;
    background-color: #333;
    color: #FFF;
    border: none;
    border-radius: 50%;
    font-size: 1.5rem;
    cursor: pointer;
    opacity: 0;
    pointer-events: none;
    transition: all 0.3s ease;
    z-index: 999;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.back-to-top:hover {
    background-color: #666;
    transform: translateY(-3px);
    box-shadow: 0 6px 16px rgba(0, 0, 0, 0.2);
}

/* ============================================
   RESPONSIVE DESIGN
   ============================================ */

@media screen and (max-width: 768px) {
    .nav-header {
        padding: 1rem 0;
    }

    .main-nav {
        gap: 1.5rem;
        padding: 0 1rem;
    }

    .nav-link {
        font-size: 0.85rem;
    }

    .hero-section {
        min-height: 90vh;
        padding: 6rem 1.5rem 3rem;
    }

    .hero-image {
        width: 200px;
        height: 200px;
        margin-bottom: 2rem;
    }

    .hero-headline {
        margin-bottom: 1.5rem;
    }

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

    section {
        padding: 4rem 0;
    }

    .section-container {
        padding: 0 1.5rem;
    }

    .section-title {
        margin-bottom: 3rem;
        font-size: 1.8rem;
    }

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

    .research-card {
        padding: 2rem;
    }

    .card-title {
        font-size: 1.2rem;
    }

    .back-to-top {
        width: 45px;
        height: 45px;
        bottom: 1.5rem;
        right: 1.5rem;
        font-size: 1.3rem;
    }

    .cv-download-btn {
        padding: 0.9rem 2rem;
        font-size: 0.85rem;
    }
}

@media screen and (max-width: 480px) {
    .main-nav {
        gap: 1rem;
        font-size: 0.8rem;
    }

    .nav-link {
        font-size: 0.75rem;
    }

    .hero-section {
        padding: 5rem 1rem 2rem;
    }

    .hero-image {
        width: 150px;
        height: 150px;
        margin-bottom: 1.5rem;
    }

    .section-container {
        padding: 0 1rem;
    }

    .research-card {
        padding: 1.5rem;
    }

    .read-more-btn {
        padding: 0.65rem 1.5rem;
        font-size: 0.8rem;
    }
}