:root {
    /* Light Theme Variables */
    --bg-color: #f8fafc;
    --bg-alt: #f1f5f9; /* Slightly darker for section contrast */
    --card-bg: rgba(255, 255, 255, 0.9);
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --accent-color: #6f42c1;
    --accent-hover: #563d7c;
    --accent-glow: rgba(111, 66, 193, 0.15);
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.05);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.05);

    --header-height: 70px;
    --container-width: 1100px; /* Widened slightly */
    --border-radius: 16px; /* Softened corners */
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

body.dark-mode {
    --bg-color: #0f172a;
    --bg-alt: #1e293b;
    --card-bg: rgba(30, 41, 59, 0.8);
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --accent-color: #a78bfa; /* Lighter purple for dark mode */
    --accent-hover: #8b5cf6;
    --accent-glow: rgba(167, 139, 250, 0.1);
    --border-color: #334155;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.3);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.3);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.3);
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: var(--header-height);
}

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
    overflow-x: hidden;
}

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

ul { list-style: none; }
img { max-width: 100%; display: block; }

.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 24px;
}

/* --- Header --- */
.header {
    height: var(--header-height);
    background-color: rgba(255, 255, 255, 0.85);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 1000;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
}

body.dark-mode .header {
    background-color: rgba(15, 23, 42, 0.85);
}

.header-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 1.5rem;
}

.logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: -0.02em;
}

.navbar {
    display: flex;
    gap: 2rem;
}

.navbar a {
    font-weight: 500;
    font-size: 0.9rem;
    color: var(--text-secondary);
    position: relative;
}

.navbar a:hover, .navbar a.active {
    color: var(--accent-color);
}

/* Underline animation for links */
.navbar a::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    bottom: -4px;
    left: 0;
    background-color: var(--accent-color);
    transition: width 0.3s ease;
}

.navbar a:hover::after {
    width: 100%;
}

.theme-btn, .mobile-menu-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    cursor: pointer;
    font-size: 1.2rem;
    color: var(--text-primary);
    transition: var(--transition);
    padding: 8px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.theme-btn:hover, .mobile-menu-btn:hover {
    background-color: var(--bg-alt);
    border-color: var(--accent-color);
    color: var(--accent-color);
}

.mobile-menu-btn {
    display: none; /* Hidden on desktop */
}

/* --- Hero Section --- */
.hero {
    padding: 80px 0;
    min-height: calc(100vh - var(--header-height));
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;
}

.hero-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 60px;
    width: 100%;
}

.hero-text {
    flex: 1;
    z-index: 2;
}

.greeting {
    color: var(--accent-color);
    font-weight: 600;
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
    display: inline-block;
    background: var(--accent-glow);
    padding: 4px 12px;
    border-radius: 20px;
}

.name {
    /* Fluid typography: scales between 3rem and 5rem */
    font-size: clamp(3rem, 5vw, 5rem); 
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: 1rem;
    background: linear-gradient(135deg, var(--text-primary) 30%, var(--text-secondary) 100%);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent; /* Fallback */
    -webkit-text-fill-color: transparent;
}

.title {
    font-size: clamp(1.2rem, 2vw, 1.8rem);
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    font-weight: 500;
}

.bio {
    font-size: 1.05rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
    max-width: 600px;
    line-height: 1.7;
}

.bio strong {
    color: var(--text-primary);
}

.social-links {
    display: flex;
    gap: 16px;
}

.social-links a {
    font-size: 1.5rem;
    color: var(--text-secondary);
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: 50%;
    display: flex;
    transition: var(--transition);
}

.social-links a:hover {
    color: white;
    background-color: var(--accent-color);
    border-color: var(--accent-color);
    transform: translateY(-3px);
}

/* Hero Image & Glow */
.hero-image {
    flex: 0 0 350px;
    display: flex;
    justify-content: center;
    position: relative;
}

.avatar-bg-glow {
    position: absolute;
    width: 100%;
    height: 100%;
    background: radial-gradient(circle, var(--accent-color) 0%, transparent 70%);
    opacity: 0.15;
    filter: blur(40px);
    z-index: 1;
    top: 0;
    left: 0;
    transform: scale(1.2);
}

.avatar-placeholder {
    width: 320px;
    height: 320px;
    border-radius: 24px;
    position: relative;
    z-index: 2;
    overflow: hidden;
    box-shadow: var(--shadow-lg);
    border: 4px solid var(--card-bg);
    transform: rotate(3deg);
    transition: var(--transition);
}

.avatar-placeholder img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.avatar-placeholder:hover {
    transform: rotate(0deg) scale(1.02);
    box-shadow: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 10px 10px -5px rgb(0 0 0 / 0.04);
}

/* --- Common Sections --- */
.section {
    padding: 100px 0;
}

.bg-alt {
    background-color: var(--bg-alt);
}

.section-header {
    margin-bottom: 50px;
    text-align: left;
}

.section-title {
    font-size: clamp(2rem, 3vw, 2.5rem);
    font-weight: 700;
    margin-bottom: 10px;
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: '';
    display: block;
    width: 40px;
    height: 4px;
    background: var(--accent-color);
    margin-top: 8px;
    border-radius: 2px;
}

.section-subtitle {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* --- Filters --- */
.filter-container {
    margin-bottom: 40px;
    overflow-x: auto;
    padding-bottom: 10px;
    -ms-overflow-style: none;
    scrollbar-width: none;
}
.filter-container::-webkit-scrollbar { display: none; }

.filter-list {
    display: flex;
    gap: 12px;
}

.filter-item {
    padding: 8px 20px;
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 50px;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition);
    white-space: nowrap;
}

.filter-item:hover, .filter-item.active {
    background-color: var(--accent-color);
    border-color: var(--accent-color);
    color: white;
    box-shadow: 0 4px 12px var(--accent-glow);
}

/* --- Cards Grid System --- */
.projects-grid, .case-studies-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 30px;
}

.project-card, .case-study-card {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 28px;
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    position: relative;
    overflow: hidden;
}

/* Glass effect for cards */
.project-card {
    backdrop-filter: blur(5px);
}

.project-card:hover, .case-study-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
    border-color: var(--accent-color);
}

.project-title, .case-study-title {
    font-size: 1.35rem;
    font-weight: 700;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.project-desc, .case-study-desc {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 20px;
    flex-grow: 1;
    line-height: 1.6;
}

.card-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 20px;
}

.tag {
    font-size: 0.75rem;
    padding: 6px 12px;
    border-radius: 6px;
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    font-weight: 500;
}

.card-link {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--accent-color);
    display: inline-flex;
    align-items: center;
    gap: 6px;
    margin-top: auto;
}

.card-link:hover {
    color: var(--accent-hover);
}

/* --- Publications --- */
.publications-list {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.publication-card {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 24px 30px;
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.publication-card:hover {
    box-shadow: var(--shadow-md);
    border-left: 4px solid var(--accent-color);
}

.pub-title {
    font-size: 1.15rem;
    font-weight: 600;
    color: var(--text-primary);
}

.pub-meta {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.pub-journal {
    font-weight: 600;
    color: var(--accent-color);
}

/* --- Buttons --- */
.view-all-container {
    margin-top: 50px;
    text-align: center;
}

.view-all-btn {
    display: inline-block;
    padding: 14px 36px;
    background-color: transparent;
    border: 2px solid var(--accent-color);
    color: var(--accent-color);
    border-radius: 50px;
    font-weight: 600;
    font-size: 1rem;
    transition: var(--transition);
}

.view-all-btn:hover {
    background-color: var(--accent-color);
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 4px 15px var(--accent-glow);
}

/* --- Footer --- */
.footer {
    padding: 40px 0;
    border-top: 1px solid var(--border-color);
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-top: auto;
}

/* --- Case Studies Page Specific --- */
.page-section { padding: 60px 0 100px; }
.back-link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: var(--text-secondary);
    margin-bottom: 30px;
    font-weight: 500;
}
.back-link:hover { color: var(--accent-color); transform: translateX(-4px); }
.page-header { margin-bottom: 60px; }

/* --- Animations --- */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in-up {
    animation: fadeInUp 0.8s ease-out forwards;
}

.delay-1 { animation-delay: 0.2s; }

/* --- Mobile / Responsive Design --- */
@media (max-width: 968px) {
    :root {
        --container-width: 100%;
    }
    
    .hero-content {
        flex-direction: column-reverse;
        text-align: center;
        gap: 40px;
    }

    .hero-image { flex: auto; }
    .hero-text { width: 100%; }
    
    .social-links {
        justify-content: center;
    }

    .bio { margin-left: auto; margin-right: auto; }
}

@media (max-width: 768px) {
    .section { padding: 60px 0; }
    
    /* Mobile Nav */
    .mobile-menu-btn { display: flex; }

    .navbar {
        position: absolute;
        top: var(--header-height);
        left: 0;
        width: 100%;
        background-color: var(--card-bg);
        flex-direction: column;
        padding: 20px;
        gap: 0;
        border-bottom: 1px solid var(--border-color);
        box-shadow: var(--shadow-lg);
        
        /* Initial State: Hidden */
        opacity: 0;
        visibility: hidden;
        transform: translateY(-10px);
        transition: var(--transition);
    }

    .navbar.active {
        opacity: 1;
        visibility: visible;
        transform: translateY(0);
    }

    .navbar a {
        padding: 16px;
        border-bottom: 1px solid var(--border-color);
        width: 100%;
        display: block;
    }
    .navbar a:last-child { border-bottom: none; }
    .navbar a:hover::after { width: 0; } /* Disable underline anim on mobile */

    /* Typography Adjustments */
    .avatar-placeholder { width: 250px; height: 250px; }
}