/* ==========================================
   GLOBAL STYLES & RESET
   ========================================== */

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

:root {
    /* Color Palette - Minimalist Professional */
    --primary-color: #2c3e50;
    --secondary-color: #34495e;
    --accent-color: #3498db;
    --text-color: #333333;
    --text-light: #666666;
    --bg-color: #ffffff;
    --bg-light: #f8f9fa;
    --border-color: #e0e0e0;
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 4px 16px rgba(0, 0, 0, 0.15);

    /* Typography */
    --font-primary: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-heading: 'Georgia', serif;

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 3rem;
    --spacing-xl: 4rem;

    /* Layout */
    --max-width: 1200px;
    --nav-height: 70px;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-primary);
    color: var(--text-color);
    line-height: 1.6;
    background-color: var(--bg-color);
}

h1,
h2,
h3,
h4,
h5,
h6 {
    font-family: var(--font-heading);
    line-height: 1.2;
    margin-bottom: var(--spacing-sm);
    color: var(--primary-color);
}

h1 {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-md);
}

h2 {
    font-size: 2rem;
    margin-top: var(--spacing-lg);
}

h3 {
    font-size: 1.5rem;
}

p {
    margin-bottom: var(--spacing-sm);
}

a {
    color: var(--accent-color);
    text-decoration: none;
    transition: color 0.3s ease;
}

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

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

/* Utility Classes */
.hidden {
    display: none !important;
}

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

#navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: var(--bg-color);
    border-bottom: 1px solid var(--border-color);
    box-shadow: var(--shadow);
    z-index: 1000;
    height: var(--nav-height);
}

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
}

.nav-logo {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--primary-color);
    font-family: var(--font-heading);
}

.nav-menu {
    display: flex;
    gap: var(--spacing-md);
    align-items: center;
}

.nav-link {
    color: var(--text-color);
    font-size: 0.95rem;
    font-weight: 500;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: 4px;
    transition: all 0.3s ease;
}

.nav-link:hover {
    background-color: var(--bg-light);
    color: var(--accent-color);
}

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 4px;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background-color: var(--primary-color);
    transition: all 0.3s ease;
    border-radius: 2px;
}

/* Language Toggle */
.lang-toggle {
    display: flex;
    gap: 0;
    background-color: var(--bg-light);
    border-radius: 6px;
    padding: 4px;
    margin-left: var(--spacing-md);
}

.lang-btn {
    padding: var(--spacing-xs) var(--spacing-sm);
    background: transparent;
    border: none;
    color: var(--text-color);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    border-radius: 4px;
    transition: all 0.3s ease;
    font-family: var(--font-primary);
}

.lang-btn:hover {
    background-color: var(--border-color);
}

.lang-btn.active {
    background-color: var(--accent-color);
    color: white;
}

/* ==========================================
   LAYOUT & SECTIONS
   ========================================== */

.section {
    min-height: 100vh;
    padding: calc(var(--nav-height) + var(--spacing-md)) var(--spacing-md) var(--spacing-md);
}

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

.section-intro {
    font-size: 1.1rem;
    color: var(--text-light);
    margin-bottom: var(--spacing-lg);
    max-width: 800px;
}

/* ==========================================
   HOME SECTION
   ========================================== */

#home {
    background: linear-gradient(135deg, var(--bg-light) 0%, var(--bg-color) 100%);
}

.home-hero {
    display: grid;
    grid-template-columns: 300px 1fr;
    gap: var(--spacing-lg);
    align-items: start;
    margin-bottom: var(--spacing-xl);
}

.portrait-container {
    position: sticky;
    top: calc(var(--nav-height) + var(--spacing-md));
    perspective: 1000px;
    cursor: pointer;
}

.portrait-flipper {
    position: relative;
    width: 100%;
    aspect-ratio: 3/4;
    transition: transform 0.8s;
    transform-style: preserve-3d;
}

.portrait-container:hover .portrait-flipper {
    transform: scale(1.02);
}

.portrait-flipper.flipped {
    transform: rotateY(180deg);
}

.portrait-image {
    position: absolute;
    width: 100%;
    height: 100%;
    border-radius: 8px;
    box-shadow: var(--shadow-hover);
    object-fit: cover;
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
}

.portrait-image.back {
    transform: rotateY(180deg);
}

.home-content {
    max-width: 100%;
}

.intro-text {
    font-size: 1.2rem;
    line-height: 1.8;
    color: var(--text-light);
    margin-bottom: var(--spacing-lg);
}

.about-section {
    margin-top: var(--spacing-lg);
}

.contact-info {
    margin-top: var(--spacing-lg);
    padding: var(--spacing-md);
    background-color: var(--bg-color);
    border-radius: 8px;
    box-shadow: var(--shadow);
}

.contact-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-md);
    margin-top: var(--spacing-md);
}

.contact-item {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.contact-item strong {
    color: var(--primary-color);
    font-weight: 600;
}

/* ==========================================
   RESEARCH & OP-EDS SECTIONS
   ========================================== */

.publications,
.opeds {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
    margin-top: var(--spacing-md);
}

.publication-item,
.oped-item {
    background-color: var(--bg-color);
    padding: var(--spacing-md);
    border-radius: 8px;
    box-shadow: var(--shadow);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.publication-item:hover,
.oped-item:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-hover);
}

.publication-title a,
.oped-title a {
    color: var(--primary-color);
    font-size: 1.3rem;
    font-weight: 600;
}

.publication-title a:hover,
.oped-title a:hover {
    color: var(--accent-color);
}

.publication-authors,
.publication-venue,
.oped-publication {
    color: var(--text-light);
    margin-bottom: var(--spacing-xs);
    font-size: 0.95rem;
}

.publication-abstract,
.oped-excerpt {
    margin-top: var(--spacing-sm);
    line-height: 1.7;
}

.abstract-content.collapsed {
    display: none;
}

.abstract-with-images {
    display: flex;
    gap: var(--spacing-lg);
    margin-top: var(--spacing-sm);
}

.abstract-text {
    flex: 1;
}

.abstract-image-viewer {
    flex: 0 0 400px;
    min-width: 300px;
}

.image-viewer-container {
    position: relative;
    width: 100%;
    aspect-ratio: 4/3;
    background-color: var(--bg-light);
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

.abstract-image {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    opacity: 0;
    transition: opacity 0.4s ease;
}

.abstract-image.active {
    opacity: 1;
}

.image-nav-btn {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    background-color: rgba(255, 255, 255, 0.9);
    border: none;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    font-size: 24px;
    color: var(--text-primary);
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2;
}

.image-nav-btn:hover {
    background-color: white;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
}

.prev-btn {
    left: 10px;
}

.next-btn {
    right: 10px;
}

.image-indicators {
    position: absolute;
    bottom: 15px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    gap: 8px;
    z-index: 2;
}

.indicator {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background-color: rgba(255, 255, 255, 0.5);
    cursor: pointer;
    transition: all 0.3s ease;
}

.indicator.active {
    background-color: white;
    box-shadow: 0 0 4px rgba(0, 0, 0, 0.3);
}

.indicator:hover {
    background-color: rgba(255, 255, 255, 0.8);
}

.image-caption {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    background-color: rgba(0, 0, 0, 0.7);
    color: white;
    padding: 10px 15px;
    font-size: 0.9rem;
    text-align: center;
    line-height: 1.4;
}

.abstract-toggle {
    background-color: var(--bg-light);
    border: 1px solid var(--border-color);
    color: var(--accent-color);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: 4px;
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    margin: var(--spacing-sm) 0;
    font-family: var(--font-primary);
}

.abstract-toggle:hover {
    background-color: var(--accent-color);
    color: white;
}

.publication-links {
    display: flex;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-sm);
}

.btn-link {
    display: inline-block;
    padding: var(--spacing-xs) var(--spacing-sm);
    background-color: var(--bg-light);
    color: var(--accent-color);
    border-radius: 4px;
    font-size: 0.9rem;
    font-weight: 500;
    transition: all 0.3s ease;
}

.btn-link:hover {
    background-color: var(--accent-color);
    color: white;
}

/* ==========================================
   TEACHING SECTION
   ========================================== */

.teaching-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
    margin-top: var(--spacing-md);
}

.teaching-item {
    background-color: var(--bg-color);
    padding: var(--spacing-md);
    border-radius: 8px;
    box-shadow: var(--shadow);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.teaching-item:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-hover);
}

.teaching-header {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-xs);
}

.teaching-title {
    color: var(--primary-color);
    font-size: 1.3rem;
    font-weight: 600;
    margin: 0;
}

.teaching-date {
    color: var(--text-light);
    font-size: 0.95rem;
    font-weight: 500;
}

.teaching-institution {
    color: var(--text-light);
    font-style: italic;
    margin-bottom: var(--spacing-sm);
    font-size: 1rem;
}

.teaching-description {
    line-height: 1.7;
    margin: 0;
}

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

.cv-download {
    margin-bottom: var(--spacing-md);
}

.btn-primary {
    display: inline-block;
    padding: var(--spacing-sm) var(--spacing-md);
    background-color: var(--accent-color);
    color: white;
    border-radius: 6px;
    font-weight: 600;
    font-size: 1rem;
    transition: all 0.3s ease;
    box-shadow: var(--shadow);
}

.btn-primary:hover {
    background-color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

.cv-embed {
    margin-top: var(--spacing-md);
}

.cv-frame {
    width: 100%;
    height: 800px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    box-shadow: var(--shadow);
}

.cv-fallback {
    margin-top: var(--spacing-sm);
    text-align: center;
    color: var(--text-light);
}

/* ==========================================
   PHOTOS SECTION
   ========================================== */

.photo-gallery {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: var(--spacing-md);
    margin-top: var(--spacing-md);
}

.photo-item {
    background-color: var(--bg-color);
    border-radius: 8px;
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    cursor: pointer;
}

.photo-item:hover {
    transform: scale(1.03);
    box-shadow: var(--shadow-hover);
}

.photo-item img {
    width: 100%;
    height: 250px;
    object-fit: cover;
    display: block;
}

.photo-caption {
    padding: var(--spacing-sm);
    font-size: 0.9rem;
    color: var(--text-light);
    text-align: center;
}

/* ==========================================
   LIGHTBOX
   ========================================== */

.lightbox {
    display: none;
    position: fixed;
    z-index: 2000;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.9);
    justify-content: center;
    align-items: center;
}

.lightbox.active {
    display: flex;
}

.lightbox-content {
    max-width: 90%;
    max-height: 80%;
    object-fit: contain;
}

.lightbox-close {
    position: absolute;
    top: 20px;
    right: 40px;
    color: white;
    font-size: 40px;
    font-weight: bold;
    cursor: pointer;
    transition: color 0.3s;
}

.lightbox-close:hover {
    color: var(--accent-color);
}

.lightbox-caption {
    position: absolute;
    bottom: 40px;
    color: white;
    text-align: center;
    width: 100%;
    padding: 0 var(--spacing-md);
}

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

footer {
    background-color: var(--primary-color);
    color: white;
    text-align: center;
    padding: var(--spacing-md);
}

footer p {
    margin: 0;
}

/* ==========================================
   RESPONSIVE DESIGN - TABLET
   ========================================== */

@media (max-width: 768px) {
    :root {
        --spacing-lg: 2rem;
        --spacing-xl: 3rem;
    }

    h1 {
        font-size: 2rem;
    }

    h2 {
        font-size: 1.75rem;
    }

    h3 {
        font-size: 1.25rem;
    }

    .nav-menu {
        position: fixed;
        left: -100%;
        top: var(--nav-height);
        flex-direction: column;
        background-color: var(--bg-color);
        width: 100%;
        text-align: center;
        transition: left 0.3s ease;
        box-shadow: var(--shadow);
        padding: var(--spacing-md) 0;
        gap: 0;
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-link {
        width: 100%;
        padding: var(--spacing-sm);
        border-radius: 0;
    }

    .hamburger {
        display: flex;
    }

    .hamburger.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }

    .hamburger.active span:nth-child(2) {
        opacity: 0;
    }

    .hamburger.active span:nth-child(3) {
        transform: rotate(-45deg) translate(7px, -6px);
    }

    .lang-toggle {
        position: absolute;
        top: calc(var(--nav-height) + 10px);
        right: var(--spacing-md);
        z-index: 999;
    }

    .home-hero {
        grid-template-columns: 1fr;
        gap: var(--spacing-md);
    }

    .portrait-container {
        position: relative;
        top: 0;
        max-width: 300px;
        margin: 0 auto;
    }

    .abstract-with-images {
        flex-direction: column;
    }

    .abstract-image-viewer {
        flex: 1;
        width: 100%;
    }

    .photo-gallery {
        grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
        gap: var(--spacing-sm);
    }

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

    .teaching-header {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--spacing-xs);
    }
}

/* ==========================================
   RESPONSIVE DESIGN - MOBILE
   ========================================== */

@media (max-width: 480px) {
    :root {
        --spacing-md: 1.5rem;
        --spacing-lg: 1.5rem;
        --spacing-xl: 2rem;
        --nav-height: 60px;
    }

    .section {
        padding: calc(var(--nav-height) + var(--spacing-md)) var(--spacing-sm) var(--spacing-md);
    }

    h1 {
        font-size: 1.75rem;
    }

    h2 {
        font-size: 1.5rem;
    }

    .nav-logo {
        font-size: 1.1rem;
    }

    .home-hero {
        grid-template-columns: 1fr;
    }

    .portrait-container {
        max-width: 250px;
    }

    .portrait-image {
        aspect-ratio: 1;
    }

    .photo-gallery {
        grid-template-columns: 1fr;
    }

    .photo-item img {
        height: 200px;
    }

    .cv-frame {
        height: 600px;
    }

    .publication-links {
        flex-wrap: wrap;
    }

    .lightbox-close {
        right: 20px;
        font-size: 30px;
    }
}

/* ==========================================
   ACCESSIBILITY
   ========================================== */

@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }

    html {
        scroll-behavior: auto;
    }
}

/* Focus visible for keyboard navigation */
a:focus-visible,
button:focus-visible {
    outline: 2px solid var(--accent-color);
    outline-offset: 2px;
}