:root {
    --bg-color: #050505;
    --text-color: #ffffff;
    --text-secondary: #a0a0a0;
    --accent-color: #00f2ff;
    --accent-glow: rgba(0, 242, 255, 0.3);
    --glass-bg: rgba(255, 255, 255, 0.03);
    --glass-border: rgba(255, 255, 255, 0.05);
    --card-hover: rgba(255, 255, 255, 0.08);
    --font-main: 'Inter', sans-serif;
    --font-heading: 'Playfair Display', serif;
    --transition: all 0.3s ease;
}

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

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

/* Typography */
h1,
h2,
h3,
h4,
h5,
h6 {
    font-family: var(--font-heading);
    font-weight: 700;
    line-height: 1.2;
}

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

/* Utilities */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

.section-padding {
    padding: 4rem 0;
}

.text-gradient {
    background: linear-gradient(90deg, #fff, var(--text-secondary));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

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

/* Navigation */
nav {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    padding: 1.5rem 0;
    transition: var(--transition);
}

nav.scrolled {
    background: rgba(5, 5, 5, 0.8);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--glass-border);
    padding: 1rem 0;
}

.nav-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-family: var(--font-heading);
    font-size: 1.5rem;
    font-weight: 700;
    letter-spacing: 1px;
}

.logo-img {
    height: 30px;
    width: auto;
    display: block;
}

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

.nav-links {
    display: flex;
    gap: 2rem;
}

.nav-links a {
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    opacity: 0.7;
}

.nav-links a:hover {
    opacity: 1;
    color: var(--accent-color);
}

/* Hero Section */
.hero {
    position: relative;
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.video-container {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
}

.video-bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    opacity: 0;
    transition: opacity 1s ease-in-out;
}

.video-bg.active {
    opacity: 0.6;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(to bottom, rgba(5, 5, 5, 0.3), rgba(5, 5, 5, 1));
    z-index: 0;
}

.hero-content {
    position: relative;
    z-index: 1;
    text-align: center;
    max-width: 1200px;
    padding: 0 2rem;
}

.hero h1 {
    font-size: 4rem;
    margin-bottom: 1rem;
    letter-spacing: -1px;
    line-height: 1.1;
}

.hero p {
    font-size: 1.5rem;
    color: var(--text-secondary);
    margin-bottom: 3rem;
    font-weight: 300;
}

.btn {
    display: inline-block;
    padding: 1rem 2.5rem;
    border: 1px solid var(--glass-border);
    background: var(--glass-bg);
    backdrop-filter: blur(5px);
    border-radius: 50px;
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 2px;
    margin: 0 1rem;
    transition: var(--transition);
}

.btn:hover {
    background: var(--accent-color);
    color: #000;
    border-color: var(--accent-color);
    box-shadow: 0 0 20px var(--accent-glow);
}

.btn-secondary {
    background: transparent;
    border-color: rgba(255, 255, 255, 0.3);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.1);
    color: #fff;
    border-color: #fff;
    box-shadow: none;
}

/* Paper Button with Text Swap */
.btn-paper {
    position: relative;
}

.btn-text-hover {
    display: none;
}

.btn-paper:hover .btn-text {
    display: none;
}

.btn-paper:hover .btn-text-hover {
    display: inline;
}

/* Abstract Section */
.abstract {
    background: var(--bg-color);
    padding-top: 4rem;
    /* Reduced from default 8rem */
}

.section-title {
    font-size: 2.5rem;
    margin-bottom: 3rem;
    text-align: center;
    position: relative;
    z-index: 2;
}

.subsection-title {
    font-size: 2.5rem;
    margin: 10rem 0 1.5rem;
    text-align: center;
    color: var(--text-primary);
    position: relative;
    z-index: 2;
}

/* Technique Tags */
.technique-tags {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.technique-tag {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--glass-border);
    color: var(--text-secondary);
    padding: 0.75rem 1.5rem;
    border-radius: 2rem;
    cursor: pointer;
    transition: var(--transition);
    font-size: 0.95rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.technique-tag:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.3);
    color: var(--text-primary);
}

.technique-tag.active {
    background: rgba(255, 69, 0, 0.2);
    border-color: var(--accent-color);
    color: var(--accent-color);
}

.technique-tag i {
    font-size: 1rem;
}

/* Technique Carousel */
.technique-carousel {
    position: relative;
    max-width: 1200px;
    margin: 0 auto;
    overflow: hidden;
    border-radius: 1rem;
}

.carousel-track {
    display: flex;
    transition: transform 0.6s ease-in-out;
}

.carousel-slide {
    min-width: 100%;
    position: relative;
    display: none;
}

.carousel-slide.active {
    display: block;
}

.carousel-image {
    width: 100%;
    height: auto;
    aspect-ratio: 16 / 10;
    object-fit: contain;
    display: block;
    border-radius: 1rem;
}

.carousel-caption {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    background: linear-gradient(to top, rgba(0, 0, 0, 0.9) 0%, rgba(0, 0, 0, 0.7) 70%, transparent 100%);
    color: var(--text-primary);
    padding: 3rem 2rem 2rem;
    border-radius: 0 0 1rem 1rem;
    opacity: 0;
    transition: opacity 0.3s ease, transform 0.3s ease;
    transform: translateY(10px);
}

.carousel-slide:hover .carousel-caption {
    opacity: 1;
    transform: translateY(0);
}

.carousel-caption h4 {
    font-size: 1.5rem;
    margin-bottom: 0.75rem;
    color: var(--accent-color);
}

.carousel-caption p {
    font-size: 0.95rem;
    line-height: 1.6;
    color: var(--text-secondary);
    margin: 0;
}

.abstract-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: justify;
    font-size: 1.1rem;
    color: var(--text-secondary);
    padding: 2rem;
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 1rem;
}

/* Background Images */
.method-section,
.results-section,
.challenge-section,
.opportunity-section,
.crisis-section {
    position: relative;
    overflow: hidden;
}

.bg-image {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
    /* Parallax effect */
    opacity: 0.15;
    z-index: 0;
}

/* Darker background for challenge section to highlight severity */
.challenge-section .bg-image {
    opacity: 0.25;
}

.bg-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(to bottom, var(--bg-color), transparent, var(--bg-color));
    z-index: 1;
}

.method-section .container,
.results-section .container,
.challenge-section .container,
.opportunity-section .container,
.crisis-section .container {
    position: relative;
    z-index: 2;
}

/* Challenge Grid */
.challenge-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 3rem;
    max-width: 1200px;
    margin: 0 auto;
}

.challenge-card {
    text-align: center;
    padding: 2.5rem;
    background: rgba(5, 5, 5, 0.7);
    border: 1px solid var(--glass-border);
    border-radius: 1rem;
    transition: var(--transition);
}

.challenge-card:hover {
    transform: translateY(-10px);
    background: rgba(255, 255, 255, 0.05);
    border-color: rgba(255, 69, 0, 0.3);
}

.opportunity-card:hover {
    border-color: rgba(0, 242, 255, 0.3);
}

.challenge-icon-container {
    margin-bottom: 2rem;
    display: flex;
    justify-content: center;
    align-items: center;
}

.challenge-icon {
    width: 360px;
    height: 360px;
    object-fit: cover;
    border-radius: 1rem;
    transition: var(--transition);
}

/* Both challenge cards should have consistent sizing and alignment */
.challenge-card h3 {
    min-height: 4.8rem;
    display: flex;
    align-items: center;
    justify-content: center;
}

.challenge-card p {
    min-height: 5.5rem;
}

/* Opportunity card image should be taller to fit its aspect ratio */
.opportunity-card .challenge-icon-container {
    height: 360px;
}

.opportunity-card .challenge-icon {
    height: 100%;
    object-fit: contain;
}

/* Reveal effect for curtain transition */
.reveal-container {
    position: relative;
    overflow: hidden;
    width: 360px;
    height: 360px;
    margin: 0 auto 2rem;
}

.base-image {
    display: block;
    width: 100%;
    height: 100%;
    object-fit: contain;
}

.reveal-layer {
    position: absolute;
    top: 0;
    left: 0;
    width: 0%;
    height: 100%;
    overflow: hidden;
    transition: width 0.3s ease-out;
}

.reveal-layer .reveal-image {
    position: absolute;
    top: 0;
    left: 0;
    width: 360px;
    height: 360px;
    object-fit: contain;
}

/* Citation styling */
.citation {
    margin-top: 1rem;
    font-size: 0.85rem;
    font-style: italic;
}

.citation a {
    color: var(--accent-color);
    text-decoration: underline;
    opacity: 0.8;
}

.citation a:hover {
    opacity: 1;
}

.challenge-card:hover .challenge-icon {
    transform: scale(1.05);
}

.challenge-card h3 {
    font-size: 1.8rem;
    margin-bottom: 1rem;
    font-family: var(--font-main);
    font-weight: 600;
}

.challenge-card p {
    color: var(--text-secondary);
    font-size: 1rem;
    line-height: 1.6;
}

/* Crisis Section */
.crisis-section .bg-image {
    opacity: 0.3;
}

.crisis-subtitle {
    text-align: center;
    font-size: 1.2rem;
    color: var(--text-secondary);
    margin: -2rem auto 4rem;
    max-width: 600px;
}

.crisis-stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 3rem;
    max-width: 1200px;
    margin: 0 auto;
}

.crisis-stat-item {
    text-align: center;
    padding: 3rem 2rem;
    background: rgba(5, 5, 5, 0.85);
    border: 1px solid var(--glass-border);
    border-radius: 1rem;
    transition: var(--transition);
}

.crisis-stat-item:hover {
    transform: translateY(-10px);
    background: rgba(20, 20, 20, 0.9);
    border-color: rgba(255, 69, 0, 0.5);
    box-shadow: 0 10px 40px rgba(255, 69, 0, 0.2);
}

.crisis-stat-icon {
    font-size: 3rem;
    color: #ff4500;
    margin-bottom: 1.5rem;
}

.crisis-stat-item h3 {
    font-size: 4rem;
    color: #ff4500;
    margin-bottom: 0.5rem;
    font-family: var(--font-main);
}

.crisis-stat-label {
    text-transform: uppercase;
    letter-spacing: 2px;
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: 0.75rem;
}

.crisis-stat-detail {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.5;
    margin: 0;
}



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

.card {
    background: rgba(5, 5, 5, 0.7);
    /* Darker background for readability */
    backdrop-filter: blur(10px);
    border: 1px solid var(--glass-border);
    padding: 2.5rem;
    border-radius: 1rem;
    transition: var(--transition);
}

.card:hover {
    transform: translateY(-10px);
    background: rgba(255, 255, 255, 0.05);
    border-color: rgba(255, 255, 255, 0.1);
}

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

.card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    font-family: var(--font-main);
}

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

/* Card Image Container with Hover Text Overlay */
.card-image-container {
    position: relative;
    width: 100%;
    border-radius: 0.5rem;
    overflow: hidden;
    margin-top: 1rem;
}

.card-image {
    width: 100%;
    height: auto;
    display: block;
    transition: var(--transition);
}

.card-text-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.9);
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1.5rem;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.card-image-container:hover .card-text-overlay {
    opacity: 1;
}

.card-text-overlay p {
    font-size: 0.9rem;
    line-height: 1.6;
    margin: 0;
}

/* Results Section */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 2rem;
    text-align: center;
    margin-top: 3rem;
}

@media (max-width: 900px) {
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 480px) {
    .stat-item h3 {
        font-size: 2.5rem !important;
    }
}

.stat-item h3 {
    font-size: 3.5rem;
    color: var(--accent-color);
    margin-bottom: 0.5rem;
    font-family: var(--font-main);
}

.stat-item p {
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
    font-size: 0.8rem;
}

/* Footer */
footer {
    background: var(--dark-bg);
    padding: 2rem 0;
    text-align: center;
    border-top: 1px solid var(--glass-border);
}

.footer-links {
    margin-bottom: 1.5rem;
}

.footer-links a {
    color: var(--text-color);
    font-size: 1.5rem;
    margin: 0 1rem;
    transition: var(--transition);
}

.footer-links a:hover {
    color: var(--accent-color);
    transform: translateY(-3px);
}

.footer-links a.grayed {
    color: #555;
    pointer-events: none;
}

.footer-links a.grayed:hover {
    color: #555;
    transform: none;
}

.footnotes {
    margin: 1.5rem 0;
    padding: 1rem 0;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    font-size: 0.85rem;
    color: var(--text-secondary);
    text-align: left;
}

.footnotes p {
    margin: 0.5rem 0;
}

.footnotes a {
    color: var(--accent-color);
    text-decoration: underline;
    opacity: 0.8;
}

.footnotes a:hover {
    opacity: 1;
}

/* Inline footnote reference styling */
.inline-footnote {
    color: var(--accent-color);
    text-decoration: none;
    border-bottom: 1px dotted var(--accent-color);
    transition: var(--transition);
}

.inline-footnote:hover {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
}

footer p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

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

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

/* Drone Sketch */
.drone-sketch-container {
    text-align: center;
    margin-bottom: 3rem;
    mix-blend-mode: lighten;
    /* Helps blend if we invert */
}

.drone-sketch {
    max-width: 100%;
    height: auto;
    max-height: 450px;
    filter: invert(1) grayscale(1);
    /* Invert white bg to black, black lines to white */
    opacity: 0.9;
    transition: var(--transition);
}

.drone-sketch:hover {
    transform: scale(1.02);
    opacity: 1;
}

/* Scenario Scroll */
.scenario-container {
    width: 100%;
    overflow: hidden;
    margin-bottom: 3rem;
    border-radius: 1rem;
    border: 1px solid var(--glass-border);
    background: rgba(0, 0, 0, 0.3);
}

.scenario-scroll {
    display: flex;
    width: fit-content;
    animation: scrollScenario 25s linear infinite;
}

.scenario-container:hover .scenario-scroll {
    animation-play-state: paused;
}

.scenario-scroll img {
    height: 400px;
    /* Adjust based on image aspect ratio */
    width: auto;
    max-width: none;
    display: block;
}

@keyframes scrollScenario {
    0% {
        transform: translateX(0);
    }

    100% {
        transform: translateX(-50%);
        /* Move by half the width (since we duplicated the image) */
    }
}

/* Responsive */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 2.5rem;
    }

    .hero p {
        font-size: 1.1rem;
    }

    .nav-links {
        display: none;
        /* Simple mobile hide for now */
    }

    .btn {
        display: block;
        margin: 1rem auto;
        width: 100%;
        max-width: 300px;
    }

    .scenario-scroll img {
        height: 250px;
    }
}

/* Add these to style.css */

/* Navigation Disabled Link */
.nav-item-disabled {
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    opacity: 0.5;
    cursor: default;
    color: var(--text-color);
}

/* Hero Authors */
.hero-authors {
    display: flex;
    justify-content: center;
    gap: 0.5rem 1rem;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}

.author:not(:last-child)::after {
    content: ",";
}

.author {
    position: relative;
    font-size: 1.1rem;
    color: var(--text-color);
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
    text-decoration: none;
}

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

.author-avatar {
    position: absolute;
    bottom: 120%;
    left: 50%;
    transform: translateX(-50%) translateY(10px);
    width: 100px;
    height: 100px;
    border-radius: 50%;
    border: 2px solid var(--accent-color);
    object-fit: cover;
    opacity: 0;
    pointer-events: none;
    transition: all 0.3s ease;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.5);
    z-index: 10;
    background: #000;
}

.author:hover .author-avatar {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}

.author.hover-active {
    color: var(--accent-color);
}

.author.hover-active .author-avatar {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}

/* Acceptance Note */
.hero .acceptance-note {
    font-size: 0.75rem;
    color: var(--accent-color);
    margin-bottom: 2.5rem;
    font-style: italic;
    opacity: 0.8;
}

.university {
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
    font-weight: 300;
}

/* Footer Logo */
.footer-logo-container {
    margin: 2rem 0;
    display: flex;
    justify-content: center;
    gap: 2rem;
    align-items: center;
}

.footer-logo {
    height: 60px;
    width: auto;
    opacity: 0.8;
    transition: var(--transition);
}

.footer-logo:hover {
    opacity: 1;
}

/* Mobile Optimization */
@media (max-width: 768px) {
    .container {
        padding: 0 1rem;
    }

    .menu-toggle {
        display: block;
        position: relative;
        z-index: 1002;
    }

    .nav-links {
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background: #050505;
        flex-direction: column;
        align-items: center;
        padding: 2rem 0;
        gap: 1.5rem;
        border-bottom: 1px solid var(--glass-border);
        display: none;
        /* Hide by default */
        z-index: 1001;
    }

    .nav-links.active {
        display: flex;
        /* Show when active */
        animation: slideDown 0.3s ease forwards;
    }

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

        to {
            opacity: 1;
            transform: translateY(0);
        }
    }

    .hero h1 {
        font-size: clamp(2rem, 8vw, 3rem);
        /* Dynamic scaling */
    }
}

/* Hero Title Split Layout */
.title-line-1 {
    display: block;
    text-align: left;
}

.title-break {
    display: block;
    text-align: right;
}

/* Landscape Mode Optimization */
@media (max-height: 600px) {
    .section-padding {
        padding: 3rem 0;
    }

    .hero {
        padding-top: 4rem;
        /* Clear navbar */
    }

    .hero h1 {
        font-size: 2.5rem;
        margin-bottom: 0.5rem;
    }

    .title-line-1,
    .title-break {
        display: inline;
        /* Single line */
        text-align: center;
    }

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

    .hero-authors {
        margin-bottom: 1rem;
    }

    .hero .acceptance-note {
        margin-bottom: 1.5rem;
    }
}