:root {
    /* Premium Dark Mode HSL Palette */
    --bg-color: hsl(220, 25%, 10%); /* Deep charcoal/blue */
    --bg-surface: hsl(220, 25%, 15%); /* Slightly lighter surface */
    --bg-alt: hsl(220, 25%, 12%);
    --bg-glass: hsla(220, 25%, 15%, 0.7);
    
    --text-primary: hsl(0, 0%, 95%);
    --text-secondary: hsl(220, 10%, 70%);
    --text-muted: hsl(220, 10%, 55%);
    
    --accent-primary: hsl(190, 80%, 60%); /* Vibrant Teal/Cyan */
    --accent-primary-hover: hsl(190, 80%, 50%);
    --accent-secondary: hsl(260, 70%, 70%); /* Soft Purple */
    
    --border-color: hsla(220, 20%, 30%, 0.5);
    
    /* Typography */
    --font-heading: 'Outfit', sans-serif;
    --font-body: 'Inter', sans-serif;
    
    /* Variables */
    --max-width: 1200px;
    --nav-height: 80px;
    --border-radius: 12px;
    --transition-fast: 0.2s ease;
    --transition-normal: 0.4s cubic-bezier(0.25, 1, 0.5, 1);
}

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

html {
    scroll-behavior: smooth;
}

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

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

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

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

.container {
    width: 90%;
    max-width: var(--max-width);
    margin: 0 auto;
}

.section-padding {
    padding: 100px 0;
}

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

/* Navigation - Glassmorphism */
#navbar {
    position: fixed;
    top: 0;
    width: 100%;
    height: var(--nav-height);
    background: var(--bg-glass);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    transition: transform 0.3s ease;
}

#navbar.scrolled-up {
    transform: translateY(0);
}

#navbar.scrolled-down {
    transform: translateY(-100%);
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
    width: 90%;
    max-width: var(--max-width);
    margin: 0 auto;
}

.logo {
    font-family: var(--font-heading);
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--text-primary);
    letter-spacing: -1px;
}

.logo::after {
    content: '';
    color: var(--accent-primary);
}

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

.nav-links a {
    color: var(--text-secondary);
    font-size: 0.95rem;
    font-weight: 500;
    position: relative;
}

.nav-links a::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    bottom: -4px;
    left: 0;
    background-color: var(--accent-primary);
    transition: width var(--transition-normal);
}

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

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

.hamburger {
    display: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-primary);
}

/* Hero Section */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    position: relative;
    padding-top: var(--nav-height);
    background: radial-gradient(circle at top right, hsla(260, 70%, 70%, 0.1), transparent 40%),
                radial-gradient(circle at bottom left, hsla(190, 80%, 60%, 0.15), transparent 40%);
}

.hero-content {
    max-width: 800px;
}

.greeting {
    font-family: var(--font-heading);
    color: var(--accent-primary);
    font-size: 1.2rem;
    font-weight: 500;
    margin-bottom: 1rem;
    text-transform: uppercase;
    letter-spacing: 2px;
}

.name {
    font-size: clamp(3rem, 8vw, 5.5rem);
    font-weight: 800;
    margin-bottom: 0.5rem;
    letter-spacing: -2px;
    background: linear-gradient(135deg, var(--text-primary) 0%, var(--text-secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.title {
    font-size: clamp(1.5rem, 4vw, 2.5rem);
    font-weight: 400;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.credentials {
    display: flex;
    gap: 0.8rem;
    align-items: center;
    margin-bottom: 2rem;
    color: var(--accent-secondary);
    font-family: var(--font-heading);
    font-weight: 500;
    font-size: 1.1rem;
    flex-wrap: wrap;
}

.summary {
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: 3rem;
    max-width: 700px;
}

.contact-links {
    display: flex;
    gap: 1.5rem;
    align-items: center;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.8rem 1.8rem;
    border-radius: 30px;
    font-weight: 500;
    font-family: var(--font-heading);
    transition: all var(--transition-fast);
    cursor: pointer;
}

.btn-primary {
    background-color: var(--accent-primary);
    color: var(--bg-color);
    border: 2px solid var(--accent-primary);
}

.btn-primary:hover {
    background-color: transparent;
    color: var(--accent-primary);
    transform: translateY(-2px);
    box-shadow: 0 10px 20px hsla(190, 80%, 60%, 0.2);
}

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

.btn-outline:hover {
    border-color: var(--text-primary);
    transform: translateY(-2px);
}

.btn-text {
    color: var(--text-secondary);
}

.btn-text:hover {
    color: var(--accent-primary);
}

.btn-text i {
    transition: transform var(--transition-fast);
}

.btn-text:hover i {
    transform: translateX(4px);
}

.scroll-indicator {
    position: absolute;
    bottom: 40px;
    left: 50%;
    transform: translateX(-50%);
    animation: bounce 2s infinite;
}

.scroll-indicator a {
    color: var(--text-muted);
    font-size: 1.5rem;
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% { transform: translateY(0); }
    40% { transform: translateY(-15px); }
    60% { transform: translateY(-7px); }
}

/* Section Headers */
.section-header {
    margin-bottom: 4rem;
}

.section-subtitle {
    font-family: var(--font-heading);
    color: var(--accent-primary);
    text-transform: uppercase;
    letter-spacing: 2px;
    font-size: 0.9rem;
    font-weight: 500;
    display: block;
    margin-bottom: 0.5rem;
}

.section-title {
    font-size: 2.5rem;
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 0;
    width: 60px;
    height: 4px;
    background: var(--accent-primary);
    border-radius: 2px;
}

.sub-heading {
    font-size: 1.5rem;
    margin-bottom: 2rem;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.sub-heading i {
    color: var(--accent-secondary);
}

/* Timeline (Experience) */
.timeline {
    position: relative;
    max-width: 900px;
    margin: 0 auto;
}

.timeline::before {
    content: '';
    position: absolute;
    top: 0;
    left: 31px;
    height: 100%;
    width: 2px;
    background: var(--border-color);
}

.timeline-item {
    position: relative;
    margin-bottom: 3rem;
    padding-left: 80px;
}

.timeline-dot {
    position: absolute;
    top: 5px;
    left: 24px;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: var(--bg-surface);
    border: 3px solid var(--accent-primary);
    z-index: 2;
    transition: all var(--transition-fast);
}

.timeline-item:hover .timeline-dot {
    background: var(--accent-primary);
    box-shadow: 0 0 15px var(--accent-primary);
}

.timeline-content {
    background: var(--bg-surface);
    padding: 2rem;
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
    transition: transform var(--transition-normal), box-shadow var(--transition-normal);
}

.timeline-item:hover .timeline-content {
    transform: translateX(10px);
    border-color: hsla(190, 80%, 60%, 0.3);
    box-shadow: 0 10px 30px rgba(0,0,0,0.5);
}

.timeline-date {
    font-family: var(--font-heading);
    color: var(--accent-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.timeline-content .role {
    font-size: 1.5rem;
    margin-bottom: 0.2rem;
}

.timeline-content .company {
    font-size: 1.1rem;
    color: var(--text-secondary);
    font-weight: 400;
    margin-bottom: 1rem;
}

.timeline-content .location {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-bottom: 1rem;
}

/* Education & Cards */
.grid-2 {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
}

.card {
    background: var(--bg-surface);
    padding: 1.5rem 2rem;
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
    margin-bottom: 1.5rem;
    transition: transform var(--transition-fast), border-color var(--transition-fast);
}

.card:hover {
    transform: translateY(-5px);
    border-color: var(--accent-secondary);
}

.card.border-highlight {
    border-left: 4px solid var(--accent-primary);
}

.card h4 {
    font-size: 1.1rem;
    margin-bottom: 0.3rem;
}

.card .inst {
    color: var(--accent-secondary);
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
}

.card .date {
    font-family: var(--font-heading);
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-bottom: 0.5rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.card .note {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-top: 0.5rem;
    font-style: italic;
}

.card .description {
    font-size: 0.95rem;
    color: var(--text-secondary);
    margin-top: 0.8rem;
}

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

.feature-card {
    background: var(--bg-surface);
    padding: 2.5rem 2rem;
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
    position: relative;
    overflow: hidden;
    transition: all var(--transition-normal);
    z-index: 1;
}

.feature-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, hsla(190, 80%, 60%, 0.1) 0%, transparent 100%);
    opacity: 0;
    transition: opacity var(--transition-normal);
    z-index: -1;
}

.feature-card:hover {
    transform: translateY(-8px);
    border-color: var(--accent-primary);
    box-shadow: 0 15px 30px rgba(0,0,0,0.4);
}

.feature-card:hover::before {
    opacity: 1;
}

.card-icon {
    font-size: 2rem;
    color: var(--accent-primary);
    margin-bottom: 1.5rem;
}

.date-badge {
    position: absolute;
    top: 2rem;
    right: 2rem;
    background: var(--bg-alt);
    padding: 0.3rem 0.8rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-family: var(--font-heading);
    color: var(--text-muted);
    border: 1px solid var(--border-color);
}

.feature-card h3 {
    font-size: 1.2rem;
    margin-bottom: 1rem;
}

.feature-card p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* Publications - Book Showcase */
.book-showcase {
    display: flex;
    background: var(--bg-surface);
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
    overflow: hidden;
    max-width: 900px;
    margin: 0 auto;
}

.book-cover {
    flex: 0 0 300px;
    background: linear-gradient(135deg, hsl(230, 20%, 20%), hsl(220, 30%, 15%));
    padding: 2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    border-right: 1px solid var(--border-color);
}

.cover-design {
    width: 100%;
    aspect-ratio: 2/3;
    background: linear-gradient(to bottom right, var(--bg-color), var(--bg-alt));
    border: 1px solid hsla(0,0%,100%,0.1);
    box-shadow: 10px 10px 20px rgba(0,0,0,0.5), -1px -1px 2px hsla(0,0%,100%,0.1);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: 2rem;
    text-align: center;
    border-radius: 4px;
    border-left: 6px solid var(--bg-surface); /* spine effect */
}

.cover-design .author {
    font-family: var(--font-heading);
    font-size: 0.8rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 2px;
    margin-bottom: auto;
}

.cover-design .book-title {
    font-size: 1.8rem;
    color: var(--text-primary);
    line-height: 1.1;
    margin: auto 0;
}

.cover-design .year {
    font-family: var(--font-heading);
    font-size: 0.9rem;
    color: var(--accent-primary);
    margin-top: auto;
}

.book-details {
    padding: 3rem;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.pub-date {
    font-family: var(--font-heading);
    color: var(--accent-secondary);
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
}

.book-details h3 {
    font-size: 2rem;
    margin-bottom: 1.5rem;
}

.book-details p {
    color: var(--text-secondary);
    font-size: 1.05rem;
}

/* Footer */
.site-footer {
    background-color: var(--bg-alt);
    border-top: 1px solid var(--border-color);
    padding: 4rem 0 2rem;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 3rem;
    flex-wrap: wrap;
    gap: 2rem;
}

.footer-brand h2 {
    font-size: 1.8rem;
    margin-bottom: 0.5rem;
}

.footer-brand p {
    color: var(--text-muted);
}

.footer-social {
    display: flex;
    gap: 1rem;
}

.footer-social a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 45px;
    height: 45px;
    border-radius: 50%;
    background: var(--bg-surface);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    font-size: 1.2rem;
}

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

.footer-bottom {
    text-align: center;
    border-top: 1px solid var(--border-color);
    padding-top: 2rem;
    color: var(--text-muted);
    font-size: 0.9rem;
}

/* Animations */
.fade-up {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.8s ease, transform 0.8s ease;
}

.fade-up.visible {
    opacity: 1;
    transform: translateY(0);
}

.reveal {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal.active {
    opacity: 1;
    transform: translateY(0);
}

/* Media Queries */
@media screen and (max-width: 900px) {
    .grid-2 {
        grid-template-columns: 1fr;
    }
    
    .book-showcase {
        flex-direction: column;
    }
    
    .book-cover {
        border-right: none;
        border-bottom: 1px solid var(--border-color);
    }
}

@media screen and (max-width: 768px) {
    .nav-links {
        position: fixed;
        top: var(--nav-height);
        left: 100%;
        width: 100%;
        height: calc(100vh - var(--nav-height));
        background: var(--bg-color);
        flex-direction: column;
        align-items: center;
        justify-content: center;
        transition: left 0.3s ease;
    }
    
    .nav-links.active {
        left: 0;
    }
    
    .hamburger {
        display: block;
    }
    
    .timeline::before {
        left: 15px;
    }
    
    .timeline-item {
        padding-left: 45px;
    }
    
    .timeline-dot {
        left: 8px;
    }
}