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

:root {
    /* Modern Color Palette */
    --primary-color: #2563eb;
    --primary-light: #3b82f6;
    --primary-dark: #1d4ed8;
    --accent-color: #f59e0b;
    --accent-light: #fbbf24;
    --success-color: #10b981;
    --danger-color: #ef4444;
    
    /* Neutral Colors */
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    
    /* Typography */
    --font-sans: 'Inter', 'Noto Sans KR', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
    
    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    
    /* Shadows */
    --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 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
}

body {
    font-family: var(--font-sans);
    line-height: 1.7;
    color: var(--gray-800);
    background: linear-gradient(135deg, var(--gray-50) 0%, #ffffff 100%);
    padding-top: 80px;
    font-size: 16px;
    letter-spacing: -0.01em;
}

/* Navigation Bar */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--gray-200);
    z-index: 1000;
    padding: var(--space-lg) 0;
    box-shadow: var(--shadow-sm);
}

.nav-container {
    max-width: 900px;
    margin: 0 auto;
    padding: 0 var(--space-xl);
    display: flex;
    justify-content: flex-end;
    align-items: center;
    gap: var(--space-lg);
    position: relative;
}

.nav-links {
    display: flex;
    gap: var(--space-lg);
}

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--space-sm);
    gap: 4px;
    z-index: 1001;
}

.hamburger-line {
    width: 24px;
    height: 2px;
    background: var(--gray-700);
    transition: all 0.3s ease;
    border-radius: 2px;
}

.mobile-menu-toggle.active .hamburger-line:nth-child(1) {
    transform: rotate(45deg) translate(6px, 6px);
}

.mobile-menu-toggle.active .hamburger-line:nth-child(2) {
    opacity: 0;
}

.mobile-menu-toggle.active .hamburger-line:nth-child(3) {
    transform: rotate(-45deg) translate(6px, -6px);
}

.nav-link {
    text-decoration: none;
    color: var(--gray-700);
    font-weight: 500;
    font-size: 0.875rem;
    padding: var(--space-sm) var(--space-lg);
    border-radius: var(--radius-xl);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
}

.nav-link::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(59, 130, 246, 0.1), transparent);
    transition: left 0.5s;
}

.nav-link:hover::before {
    left: 100%;
}

.nav-link:hover {
    background: var(--primary-color);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.nav-link.active {
    background: var(--primary-color);
    color: white;
    box-shadow: var(--shadow-md);
}

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: var(--space-3xl) var(--space-xl);
}

/* Header Section */
.header {
    margin-bottom: var(--space-3xl);
}

.profile-section {
    display: flex;
    align-items: flex-start;
    gap: var(--space-2xl);
    margin-bottom: var(--space-2xl);
    background: white;
    padding: var(--space-2xl);
    border-radius: var(--radius-2xl);
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--gray-100);
}

.profile-image {
    width: 200px;
    height: 250px;
    border-radius: var(--radius-xl);
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 3rem;
    color: white;
    flex-shrink: 0;
    overflow: hidden;
    box-shadow: var(--shadow-xl);
    position: relative;
}

.profile-image::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, transparent 0%, rgba(255, 255, 255, 0.1) 50%, transparent 100%);
    pointer-events: none;
}

.profile-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: var(--radius-xl);
}

.profile-info h1 {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--gray-900);
    margin-bottom: var(--space-sm);
    line-height: 1.2;
    letter-spacing: -0.02em;
}

.profile-info .title {
    font-size: 1.2rem;
    color: var(--gray-600);
    margin-bottom: var(--space-sm);
    font-weight: 500;
}

.profile-info .affiliation {
    font-size: 1rem;
    color: var(--gray-500);
    margin-bottom: var(--space-lg);
    line-height: 1.5;
}

.profile-info .description {
    font-size: 1rem;
    color: var(--gray-700);
    line-height: 1.7;
    margin-bottom: var(--space-xl);
    max-width: 600px;
}

.profile-info .description b {
    color: var(--primary-color);
    font-weight: 600;
}

/* Social Links */
.social-links {
    display: flex;
    gap: var(--space-md);
    flex-wrap: wrap;
    margin-top: var(--space-lg);
    justify-content: center;
}

.social-link {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    padding: var(--space-md) var(--space-lg);
    background: white;
    color: var(--gray-700);
    text-decoration: none;
    border-radius: var(--radius-xl);
    border: 1px solid var(--gray-200);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    font-weight: 500;
    font-size: 0.875rem;
    box-shadow: var(--shadow-sm);
    position: relative;
    overflow: hidden;
}

.social-link::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(37, 99, 235, 0.1), transparent);
    transition: left 0.6s;
}

.social-link:hover::before {
    left: 100%;
}

.social-link:hover {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.social-link i {
    font-size: 1rem;
    transition: transform 0.3s ease;
}

.social-link:hover i {
    transform: scale(1.1);
}

/* Section Styles */
.section {
    margin-bottom: var(--space-3xl);
    background: white;
    padding: var(--space-2xl);
    border-radius: var(--radius-2xl);
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--gray-100);
    position: relative;
    overflow: hidden;
}

.section::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--primary-light));
}

.section-title {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--gray-900);
    margin-bottom: var(--space-xl);
    padding-bottom: var(--space-md);
    position: relative;
    letter-spacing: -0.01em;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 60px;
    height: 3px;
    background: linear-gradient(90deg, var(--primary-color), var(--primary-light));
    border-radius: var(--radius-sm);
}

/* Education Section */
.education-list {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.education-item {
    display: flex;
    gap: 25px;
    align-items: flex-start;
}

.education-period {
    background: #3498db;
    color: white;
    padding: 6px 12px;
    border-radius: 15px;
    font-size: 0.85rem;
    font-weight: 500;
    white-space: nowrap;
    min-width: 120px;
    text-align: center;
}

.education-content h3 {
    font-size: 1.1rem;
    font-weight: 600;
    color: #2c3e50;
    margin-bottom: 5px;
}

.education-content .institution {
    color: #666;
    margin-bottom: 3px;
}

.education-content .advisor,
.education-content .details {
    color: #888;
    font-size: 0.9rem;
}

/* News Section */
.news-list {
    display: flex;
    flex-direction: column;
    gap: var(--space-lg);
}

.news-item {
    display: flex;
    gap: var(--space-xl);
    align-items: flex-start;
    padding: var(--space-xl);
    background: var(--gray-50);
    border-radius: var(--radius-xl);
    border: 1px solid var(--gray-200);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
}

.news-item::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: linear-gradient(180deg, var(--danger-color), #dc2626);
}

.news-item:hover {
    background: white;
    transform: translateY(-3px);
    box-shadow: var(--shadow-xl);
    border-color: var(--gray-300);
}

.news-date {
    background: linear-gradient(135deg, var(--danger-color), #dc2626);
    color: white;
    padding: var(--space-sm) var(--space-lg);
    border-radius: var(--radius-xl);
    font-size: 0.875rem;
    font-weight: 600;
    white-space: nowrap;
    min-width: 140px;
    text-align: center;
    flex-shrink: 0;
    box-shadow: var(--shadow-md);
    position: relative;
}

.news-date::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, transparent 0%, rgba(255, 255, 255, 0.2) 50%, transparent 100%);
    border-radius: var(--radius-xl);
}

.news-content p {
    margin: 0;
    color: var(--gray-800);
    font-size: 1rem;
    line-height: 1.6;
    font-weight: 400;
}

.news-content strong {
    color: var(--danger-color);
    font-weight: 600;
}

.news-links {
    margin-top: var(--space-md);
    display: flex;
    gap: var(--space-md);
    flex-wrap: wrap;
}

.news-link {
    background: white !important;
    color: var(--danger-color) !important;
    padding: var(--space-sm) var(--space-lg);
    border: 2px solid var(--danger-color);
    border-radius: var(--radius-xl);
    text-decoration: none !important;
    font-size: 0.875rem;
    font-weight: 600;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    display: inline-flex;
    align-items: center;
    gap: var(--space-sm);
    box-shadow: var(--shadow-sm);
    position: relative;
    overflow: hidden;
}

.news-link::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: var(--danger-color);
    transition: left 0.3s ease;
    z-index: -1;
}

.news-link:hover::before {
    left: 0;
}

.news-link:hover {
    color: white !important;
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.news-link i {
    font-size: 0.875rem;
    transition: transform 0.3s ease;
}

.news-link:hover i {
    transform: scale(1.1);
}

/* Publications Section */
.publications-list {
    display: flex;
    flex-direction: column;
    gap: 5px;
}

.publication-item {
    display: flex;
    gap: 20px;
    align-items: flex-start;
    margin-bottom: 15px;
}

.publication-year {
    font-size: 1.2rem;
    font-weight: 600;
    color: #3498db;
    min-width: 60px;
    text-align: left;
    flex-shrink: 0;
    padding-top: 2px;
}

.publication-venue {
    background: #e8f4fd;
    color: #2980b9;
    padding: 6px 12px;
    border-radius: 12px;
    font-size: 0.8rem;
    font-weight: 500;
    white-space: nowrap;
    min-width: 100px;
    text-align: center;
    flex-shrink: 0;
}

.publication-content h3 {
    font-size: 1rem;
    font-weight: 600;
    color: #2c3e50;
    margin-bottom: 8px;
    line-height: 1.4;
}

.publication-content .authors {
    color: #666;
    margin-bottom: 3px;
    font-size: 0.9rem;
}

.publication-content .equal-contribution {
    color: #999;
    font-size: 0.75rem;
    margin-bottom: 5px;
    font-style: italic;
}

.publication-content .venue-info {
    color: #888;
    font-size: 0.85rem;
    margin-bottom: 10px;
}

.publication-links {
    display: flex;
    gap: 10px;
}

.pub-link {
    background: transparent;
    color: #3498db;
    padding: 4px 12px;
    border: 1px solid #3498db;
    border-radius: 12px;
    text-decoration: none;
    font-size: 0.8rem;
    transition: all 0.3s ease;
    display: inline-block;
    margin: 2px 0;
}

.pub-link:hover {
    background: #3498db;
    color: white;
}

/* Experiences Section */
.experience-list {
    display: flex;
    flex-direction: column;
    gap: 25px;
}

.experience-item {
    display: flex;
    gap: 25px;
    align-items: flex-start;
}

.experience-period {
    background: #27ae60;
    color: white;
    padding: 6px 12px;
    border-radius: 15px;
    font-size: 0.85rem;
    font-weight: 500;
    white-space: nowrap;
    min-width: 120px;
    text-align: center;
    flex-shrink: 0;
    padding-top: 8px;
}

.experience-period.military {
    background: #4a5d23;
}

.experience-content h3 {
    font-size: 1.1rem;
    font-weight: 600;
    color: #2c3e50;
    margin-bottom: 5px;
}

.experience-content .institution {
    color: #666;
    margin-bottom: 10px;
}

.experience-details {
    list-style: none;
    padding-left: 0;
}

.experience-details li {
    color: #555;
    margin-bottom: 5px;
    padding-left: 15px;
    position: relative;
    font-size: 0.95rem;
}

.experience-details li::before {
    content: "•";
    color: #3498db;
    position: absolute;
    left: 0;
}

/* Research Interests */
.interests-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
}

.interest-item {
    background: #f8f9fa;
    padding: 20px;
    border-radius: 10px;
    text-align: center;
    border: 1px solid #e9ecef;
    transition: transform 0.3s ease;
}

.interest-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
}

.interest-item i {
    font-size: 2rem;
    color: #3498db;
    margin-bottom: 10px;
}

.interest-item h3 {
    font-size: 1rem;
    font-weight: 600;
    color: #2c3e50;
    margin-bottom: 8px;
}

.interest-item p {
    color: #666;
    font-size: 0.9rem;
}

/* Footer */
.footer {
    margin-top: 60px;
    padding-top: 30px;
    border-top: 1px solid #e9ecef;
    text-align: center;
    color: #888;
    font-size: 0.85rem;
}

.footer p {
    margin-bottom: 5px;
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 20px 15px;
    }
    
    /* Navigation responsive styles */
    .nav-container {
        padding: 0 var(--space-md);
        justify-content: space-between;
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
    
    .nav-links {
        position: fixed;
        top: 80px;
        left: 0;
        right: 0;
        background: rgba(255, 255, 255, 0.95);
        backdrop-filter: blur(20px);
        flex-direction: column;
        padding: var(--space-lg);
        gap: var(--space-md);
        box-shadow: var(--shadow-lg);
        border-top: 1px solid var(--gray-200);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
        z-index: 1000;
    }
    
    .nav-links.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }
    
    .nav-link {
        font-size: 1rem;
        padding: var(--space-md);
        text-align: center;
        border-radius: var(--radius-md);
        width: 100%;
    }
    
    .profile-section {
        flex-direction: column;
        align-items: center;
        text-align: center;
        gap: 20px;
    }
    
    .profile-image {
        width: 100px;
        height: 100px;
        font-size: 2.5rem;
    }
    
    .profile-info h1 {
        font-size: 1.8rem;
    }
    
    .social-links {
        justify-content: center;
    }
    
    .education-item,
    .publication-item,
    .experience-item,
    .news-item {
        flex-direction: column;
        gap: 10px;
    }
    
    .education-period,
    .experience-period,
    .news-date {
        align-self: flex-start;
        min-width: auto;
    }
    
    .publication-venue {
        align-self: flex-start;
        min-width: auto;
    }
    
    .interests-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .profile-info h1 {
        font-size: 1.5rem;
    }
    
    .section-title {
        font-size: 1.3rem;
    }
    
    /* Navigation for very small screens */
    .nav-container {
        padding: 0 var(--space-sm);
    }
    
    .nav-links {
        padding: var(--space-md);
        gap: var(--space-sm);
    }
    
    .nav-link {
        font-size: 0.9rem;
        padding: var(--space-sm);
    }
    
    .social-links {
        flex-direction: column;
        align-items: center;
    }
    
    .social-link {
        width: 200px;
        justify-content: center;
    }
}

/* Smooth scrolling and animations */
html {
    scroll-behavior: smooth;
}

/* Fade-in animation for sections */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideInLeft {
    from {
        opacity: 0;
        transform: translateX(-30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.05);
    }
}

/* Apply animations */
.section {
    animation: fadeInUp 0.6s ease-out;
}

.profile-section {
    animation: slideInLeft 0.8s ease-out;
}

.social-link:hover {
    animation: pulse 0.6s ease-in-out;
}

/* Parallax effect for background */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(circle at 20% 80%, rgba(37, 99, 235, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(59, 130, 246, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 40% 40%, rgba(245, 158, 11, 0.05) 0%, transparent 50%);
    z-index: -1;
    pointer-events: none;
}

/* Print styles */
@media print {
    .social-links {
        display: none;
    }
    
    .container {
        max-width: none;
        padding: 0;
    }
    
    .section {
        break-inside: avoid;
    }
}