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

:root {
    --bg-primary: #0f172a;
    --bg-secondary: #0a192f;
    --bg-tertiary: #1e293b;
    --bg-overlay: rgba(15, 23, 42, 0.85);
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent: #38bdf8;
    --accent-hover: #0ea5e9;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.6);
    --nav-bg: rgba(15, 23, 42, 0.95);
    --nav-border: rgba(255, 255, 255, 0.1);
    --card-border: rgba(255, 255, 255, 0.1);
    --section-divider: rgba(255, 255, 255, 0.1);
    --hero-overlay-start: rgba(15, 23, 42, 0.4);
    --hero-overlay-end: #0f172a;
    --hover-bg: rgba(255, 255, 255, 0.05);
}

[data-theme="light"] {
    --bg-primary: #f8fafc;
    --bg-secondary: #f1f5f9;
    --bg-tertiary: #ffffff;
    --bg-overlay: rgba(248, 250, 252, 0.85);
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --accent: #0284c7;
    --accent-hover: #0369a1;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.1);
    --nav-bg: rgba(248, 250, 252, 0.95);
    --nav-border: rgba(15, 23, 42, 0.1);
    --card-border: rgba(15, 23, 42, 0.1);
    --section-divider: rgba(15, 23, 42, 0.1);
    --hero-overlay-start: rgba(248, 250, 252, 0.4);
    --hero-overlay-end: #f8fafc;
    --hover-bg: rgba(0, 0, 0, 0.05);
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background-color: var(--bg-primary);
    background-image: url('research_bg.png');
    background-attachment: fixed;
    background-size: cover;
    background-position: center;
    color: var(--text-primary);
    line-height: 1.6;
}

html {
    scroll-behavior: smooth;
}

/* Navigation */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: var(--nav-bg);
    backdrop-filter: blur(10px);
    z-index: 1000;
    border-bottom: 1px solid var(--nav-border);
}

.nav-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 700;
    font-size: 1.2rem;
}

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

.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.3s;
    font-weight: 500;
}

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

.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    color: var(--text-primary);
    cursor: pointer;
    font-size: 1.5rem;
}

.theme-toggle {
    background: none;
    border: none;
    color: var(--text-primary);
    cursor: pointer;
    font-size: 1.25rem;
    padding: 0.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: color 0.3s;
}

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

/* Hero Section */
.hero {
    padding: 8rem 2rem 4rem;
    min-height: 100vh;
    display: flex;
    align-items: center;
    position: relative;
    background: url('hero_bg.png') no-repeat center center/cover;
}

.hero-content {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
    position: relative;
    z-index: 2;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: 1rem;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

.hero-stats {
    display: flex;
    gap: 2rem;
    margin-bottom: 2rem;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(to bottom, var(--hero-overlay-start), var(--hero-overlay-end)),
        radial-gradient(circle, var(--hero-overlay-start) 0%, var(--hero-overlay-end) 80%);
    pointer-events: none;
    z-index: 1;
}

.stat {
    text-align: center;
}

.stat-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--accent);
}

.stat-label {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.hero-actions {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.btn {
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    font-weight: 600;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.3s;
    border: none;
    cursor: pointer;
}

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

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

.btn-secondary {
    background: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.btn-secondary:hover {
    border-color: var(--accent);
}

.hero-image {
    display: flex;
    justify-content: center;
}

.profile-img {
    width: 100%;
    max-width: 400px;
    border-radius: 1rem;
    box-shadow: var(--shadow-lg);
    border: 2px solid rgba(255, 255, 255, 0.1);
}

/* Sections */
.section {
    padding: 4rem 2rem;
    background: var(--bg-overlay);
    position: relative;
    z-index: 2;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
}

.section-title {
    display: flex;
    align-items: center;
    margin-bottom: 40px;
}

.section-title span {
    color: var(--accent);
    font-family: inherit;
    margin-right: 15px;
    font-size: 1.5rem;
    font-weight: 600;
}

.section-title h2 {
    font-size: 2.5rem;
    font-weight: 800;
    white-space: nowrap;
    margin: 0;
}

.section-title::after {
    content: "";
    display: block;
    width: 300px;
    height: 1px;
    background: var(--section-divider);
    margin-left: 20px;
}

.section-subtitle {
    text-align: center;
    color: var(--text-secondary);
    margin-bottom: 3rem;
    font-size: 1.125rem;
}

/* Projects */


.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
}

.project-card {
    background: var(--bg-tertiary);
    padding: 2rem;
    border-radius: 1rem;
    border: 1px solid rgba(255, 255, 255, 0.1);
    transition: all 0.3s;
}

.project-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--accent);
}

.project-icon {
    width: 4rem;
    height: 4rem;
    border-radius: 0.75rem;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1.5rem;
    color: white;
    font-size: 2rem;
}

.gradient-blue {
    background: linear-gradient(135deg, #3b82f6 0%, #06b6d4 100%);
}

.gradient-purple {
    background: linear-gradient(135deg, #a855f7 0%, #ec4899 100%);
}

.gradient-green {
    background: linear-gradient(135deg, #10b981 0%, #14b8a6 100%);
}

.project-title {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.project-description {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    line-height: 1.7;
}

.project-tech {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
}

.tech-badge {
    background: rgba(59, 130, 246, 0.1);
    color: var(--accent);
    padding: 0.25rem 0.75rem;
    border-radius: 0.25rem;
    font-size: 0.875rem;
    font-weight: 500;
}

.project-link {
    color: var(--accent);
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 600;
    transition: gap 0.3s;
}

.project-link:hover {
    gap: 0.75rem;
}

/* Blog */
.blog-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
}

.blog-card {
    background: var(--bg-secondary);
    padding: 2rem;
    border-radius: 1rem;
    border: 1px solid rgba(255, 255, 255, 0.1);
    transition: all 0.3s;
}

.blog-card:hover {
    transform: translateY(-4px);
    border-color: var(--accent);
}

.blog-icon {
    color: var(--accent);
    margin-bottom: 1rem;
    font-size: 1.5rem;
}

.blog-meta {
    display: flex;
    gap: 0.5rem;
    color: var(--text-secondary);
    font-size: 0.875rem;
    margin-bottom: 1rem;
}

.blog-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.blog-excerpt {
    color: var(--text-secondary);
    margin-bottom: 1rem;
    line-height: 1.7;
}

.blog-link {
    color: var(--accent);
    text-decoration: none;
    font-weight: 600;
    transition: transform 0.3s;
    display: inline-block;
}

.blog-link:hover {
    transform: translateX(4px);
}

/* Sponsorship */


.sponsor-card {
    background: var(--bg-secondary);
    padding: 3rem;
    border-radius: 1.5rem;
    border: 1px solid rgba(255, 255, 255, 0.1);
    text-align: center;
}

.sponsor-icon {
    font-size: 4rem;
    color: #ef4444;
    margin-bottom: 1.5rem;
}

.sponsor-title {
    font-size: 2rem;
    font-weight: 800;
    margin-bottom: 1rem;
}

.sponsor-description {
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto 3rem;
    line-height: 1.8;
}

.sponsor-tiers {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.tier {
    background: var(--bg-tertiary);
    padding: 2rem;
    border-radius: 1rem;
    border: 1px solid rgba(255, 255, 255, 0.1);
    text-align: left;
}

.tier.featured {
    border-color: var(--accent);
    transform: scale(1.05);
}

.tier h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
}

.tier-price {
    font-size: 2rem;
    font-weight: 700;
    color: var(--accent);
    margin-bottom: 1rem;
}

.tier ul {
    list-style: none;
    color: var(--text-secondary);
}

.tier ul li {
    padding: 0.5rem 0;
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
}

.tier ul li:before {
    content: "✓ ";
    color: var(--accent);
    font-weight: bold;
    margin-right: 0.5rem;
}

.sponsor-buttons {
    display: flex;
    justify-content: center;
    gap: 1rem;
    flex-wrap: wrap;
}

.btn-sponsor {
    background: #ef4444;
    color: white;
}

.btn-sponsor:hover {
    background: #dc2626;
}

/* Contact Section Specific */
.contact-container {
    max-width: 700px !important;
    margin: 0 auto;
    text-align: center;
}

.contact-card {
    padding: 4rem 3rem !important;
    border-radius: 2rem !important;
}

.section-title.centered {
    justify-content: center;
}

.section-title.centered::after {
    display: none;
}

.section-title.centered span {
    margin-right: 15px;
}

/* Footer */
.footer {
    background: var(--bg-secondary);
    padding: 3rem 2rem 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
}

.footer-info h3 {
    margin-bottom: 0.5rem;
}

.footer-info p {
    color: var(--text-secondary);
}

.footer-links {
    display: flex;
    gap: 1.5rem;
}

.footer-links a {
    color: var(--text-secondary);
    transition: color 0.3s;
    font-size: 1.5rem;
}

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

.footer-bottom {
    text-align: center;
    padding: 2rem 0 4rem;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
    color: var(--text-secondary);
    font-size: 0.85rem;
    font-family: 'Inter', sans-serif;
    letter-spacing: 0.5px;
    opacity: 0.8;
}

/* Responsive */
@media (max-width: 768px) {
    .mobile-menu-btn {
        display: block;
    }

    .nav-links {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--bg-secondary);
        padding: 1rem;
        flex-direction: column;
        border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    }

    .nav-links.active {
        display: flex;
    }

    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .hero-title {
        font-size: 2.5rem;
    }

    .hero-stats {
        justify-content: center;
    }

    .hero-actions {
        justify-content: center;
    }

    .footer-content {
        flex-direction: column;
        gap: 2rem;
        text-align: center;
    }

    .sponsor-tiers {
        grid-template-columns: 1fr;
    }

    .tier.featured {
        transform: scale(1);
    }
}

/* About Section */


.about-grid {
    display: grid;
    grid-template-columns: 3fr 2fr;
    gap: 4rem;
    align-items: start;
}

.about-text p {
    margin-bottom: 1.5rem;
    color: var(--text-secondary);
    font-size: 1.1rem;
    line-height: 1.8;
}

.tech-list {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 0.75rem;
    list-style: none;
    margin-top: 2rem;
}

.tech-list li {
    padding-left: 1.5rem;
    position: relative;
    color: var(--text-secondary);
    font-weight: 500;
}

.tech-list li::before {
    content: "▹";
    position: absolute;
    left: 0;
    color: var(--accent);
}

.about-stats {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.stat-card {
    background: var(--bg-tertiary);
    padding: 2.5rem;
    border-radius: 1rem;
    text-align: center;
    border: 1px solid rgba(255, 255, 255, 0.1);
    transition: all 0.3s;
}

.stat-card:hover {
    border-color: var(--accent);
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.stat-card h3 {
    font-size: 2.5rem;
    color: var(--accent);
    margin-bottom: 0.5rem;
}

.stat-card p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

@media (max-width: 768px) {
    .about-grid {
        grid-template-columns: 1fr;
        gap: 3rem;
    }
}

/* Expertise Section */


.expertise-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
}

.expertise-card {
    background: var(--bg-tertiary);
    padding: 40px 30px;
    border-radius: 1rem;
    transition: all 0.3s;
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.expertise-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-lg);
    border-color: var(--accent);
}

.expertise-card i {
    font-size: 2rem;
    color: var(--accent);
    margin-bottom: 20px;
}

.expertise-card h3 {
    margin-bottom: 15px;
    color: var(--text-primary);
}

/* Ukraine Section */


.ukraine-banner {
    padding: 3rem;
    background: var(--bg-tertiary);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 1.5rem;
    position: relative;
    overflow: hidden;
}

.ukraine-content {
    display: flex;
    align-items: center;
    gap: 3rem;
}

.flag {
    width: 120px;
    height: 80px;
    flex-shrink: 0;
    border-radius: 4px;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.3);
}

.flag .blue {
    background-color: #0057b7;
    height: 50%;
}

.flag .yellow {
    background-color: #ffd700;
    height: 50%;
}

.ukraine-content .text h2 {
    margin-bottom: 1rem;
    font-size: 2rem;
    font-weight: 800;
}

.ukraine-content .text p {
    margin-bottom: 2rem;
    max-width: 600px;
    color: var(--text-secondary);
}

.ukraine-actions {
    display: flex;
    gap: 1.5rem;
}

@media (max-width: 768px) {
    .ukraine-content {
        flex-direction: column;
        text-align: center;
        gap: 2rem;
    }

    .ukraine-actions {
        justify-content: center;
    }
}

/* Glass Utility */
.glass {
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 12px;
}

/* Fade In Animation */
.fade-in {
    opacity: 0;
    transform: translateY(20px);
    animation: fadeInUp 0.8s ease-out forwards;
}

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