/* Root Variables - Monochromatic Theme */
:root {
    --primary-color: #000000;
    --primary-hover: #1a1a1a;
    --dark-bg: #ffffff;
    --dark-secondary: #fafafa;
    --text-primary: #1a1a1a;
    --text-secondary: #666666;
    --border-color: rgba(0, 0, 0, 0.06);
    --accent-color: #000000;
    --transition: all 0.3s ease;
}

/* Dark Theme - Inverted Grayscale */
[data-theme="dark"] {
    --primary-color: #ffffff;
    --primary-hover: #e5e5e5;
    --dark-bg: #0a0a0a;
    --dark-secondary: #141414;
    --text-primary: #f5f5f5;
    --text-secondary: #999999;
    --border-color: rgba(255, 255, 255, 0.08);
    --accent-color: #ffffff;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--dark-bg);
    color: var(--text-primary);
    line-height: 1.8;
    transition: background-color 0.4s ease, color 0.4s ease;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 40px;
}

/* Navigation */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background-color: var(--dark-bg);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    transition: var(--transition);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 40px;
}

.nav-brand {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
    letter-spacing: -0.3px;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2.5rem;
}

.nav-menu a {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 400;
    transition: var(--transition);
    font-size: 0.95rem;
}

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

.nav-controls {
    display: flex;
    gap: 1rem;
    align-items: center;
}

.theme-toggle,
.language-toggle {
    background: none;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    cursor: pointer;
    padding: 0.5rem 0.9rem;
    border-radius: 6px;
    font-size: 0.9rem;
    transition: var(--transition);
    display: flex;
    align-items: center;
    font-weight: 400;
}

.theme-toggle:hover,
.language-toggle:hover {
    border-color: var(--text-primary);
    background-color: var(--dark-secondary);
}

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 5px;
}

.hamburger span {
    width: 24px;
    height: 2px;
    background-color: var(--text-primary);
    border-radius: 2px;
    transition: var(--transition);
}

/* Hero Section */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--dark-bg);
    padding-top: 100px;
    padding-bottom: 8rem;
}

.hero-content {
    text-align: center;
    max-width: 900px;
    margin: 0 auto;
}

.hero-title {
    font-size: 4rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
    letter-spacing: -2px;
    line-height: 1.1;
    animation: fadeInUp 0.8s ease;
}

.hero-subtitle {
    font-size: 1.4rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
    animation: fadeInUp 0.8s ease 0.1s backwards;
    font-weight: 400;
    line-height: 1.6;
}

.hero-description {
    font-size: 1.2rem;
    color: var(--text-secondary);
    max-width: 700px;
    margin: 0 auto 3rem;
    animation: fadeInUp 0.8s ease 0.2s backwards;
    line-height: 1.8;
}

.hero-buttons {
    display: flex;
    gap: 1.5rem;
    justify-content: center;
    flex-wrap: wrap;
    animation: fadeInUp 0.8s ease 0.3s backwards;
}

/* Buttons - Minimal Design */
.btn {
    padding: 14px 32px;
    border-radius: 6px;
    text-decoration: none;
    font-weight: 400;
    transition: var(--transition);
    cursor: pointer;
    font-size: 1rem;
    display: inline-block;
    border: 1px solid var(--text-primary);
    color: var(--text-primary);
    background: transparent;
}

.btn:hover {
    background-color: var(--text-primary);
    color: var(--dark-bg);
}

.btn-primary {
    background-color: var(--text-primary);
    color: var(--dark-bg);
    border: 1px solid var(--text-primary);
}

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

.btn-secondary {
    border: 1px solid var(--text-primary);
    color: var(--text-primary);
    background: transparent;
}

.btn-secondary:hover {
    background-color: var(--text-primary);
    color: var(--dark-bg);
}

/* Section Titles */
.section-title {
    font-size: 3rem;
    font-weight: 600;
    text-align: center;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
    letter-spacing: -1.5px;
    line-height: 1.2;
}

.section-description {
    text-align: center;
    color: var(--text-secondary);
    max-width: 700px;
    margin: 0 auto 5rem;
    font-size: 1.15rem;
    line-height: 1.8;
}

/* About Section */
.about {
    padding: 8rem 0;
    background-color: var(--dark-secondary);
}

.about-content {
    max-width: 800px;
    margin: 0 auto;
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.about-text p {
    font-size: 1.2rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
    line-height: 1.9;
}

/* Research Section */
.research {
    padding: 8rem 0;
    background-color: var(--dark-bg);
}

.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 3rem;
}

.research-card {
    background: var(--dark-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 2.5rem;
    transition: var(--transition);
    opacity: 0;
    transform: translateY(20px);
}

.research-card:nth-child(1) {
    animation: slideInUp 0.6s ease 0.1s forwards;
}

.research-card:nth-child(2) {
    animation: slideInUp 0.6s ease 0.2s forwards;
}

.research-card:nth-child(3) {
    animation: slideInUp 0.6s ease 0.3s forwards;
}

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

.research-card h3 {
    font-size: 1.5rem;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
    font-weight: 600;
    line-height: 1.4;
}

.research-category {
    color: var(--text-secondary);
    font-size: 0.85rem;
    font-weight: 500;
    margin-bottom: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.research-date {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 1.5rem;
}

.research-description {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    line-height: 1.8;
    font-size: 1rem;
}

.research-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
}

.tag {
    background-color: var(--dark-secondary);
    color: var(--text-secondary);
    padding: 6px 12px;
    border-radius: 4px;
    font-size: 0.85rem;
    font-weight: 400;
    border: 1px solid var(--border-color);
}

/* Projects Section */
.projects {
    padding: 8rem 0;
    background-color: var(--dark-secondary);
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 3rem;
}

.project-card {
    background: var(--dark-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 2.5rem;
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    height: 100%;
    opacity: 0;
    transform: translateY(20px);
}

.project-card:nth-child(1) {
    animation: slideInUp 0.6s ease 0.1s forwards;
}

.project-card:nth-child(2) {
    animation: slideInUp 0.6s ease 0.2s forwards;
}

.project-card:nth-child(3) {
    animation: slideInUp 0.6s ease 0.3s forwards;
}

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

.project-header h3 {
    font-size: 1.5rem;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
    font-weight: 600;
    line-height: 1.4;
}

.project-category {
    color: var(--text-secondary);
    font-size: 0.85rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 1.5rem;
}

.project-description {
    color: var(--text-secondary);
    margin-bottom: 2rem;
    flex-grow: 1;
    line-height: 1.8;
    font-size: 1rem;
}

.project-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
}

.project-link {
    color: var(--text-primary);
    text-decoration: none;
    font-weight: 400;
    transition: var(--transition);
    display: inline-block;
    margin-top: 1rem;
}

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

/* Research link button */
.research-link-btn {
    background: none;
    border: none;
    cursor: pointer;
    font-family: inherit;
    font-size: 1rem;
    padding: 0;
    margin-top: 1rem;
    color: var(--text-primary);
    text-decoration: none;
    font-weight: 400;
    transition: var(--transition);
    display: inline-block;
}

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

/* Research modal - wider for text content */
.modal-research {
    max-width: 800px;
}

.modal-research .modal-description {
    font-size: 1rem;
    line-height: 1.9;
    white-space: pre-line;
}

/* Building Section */
.building {
    padding: 8rem 0;
    background-color: var(--dark-bg);
}

.building-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 3rem;
    margin-top: 2rem;
}

.building-card {
    background: var(--dark-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 2.5rem;
    transition: var(--transition);
    opacity: 0;
    transform: translateY(20px);
}

.building-card:nth-child(1) {
    animation: slideInUp 0.6s ease 0.1s forwards;
}

.building-card:nth-child(2) {
    animation: slideInUp 0.6s ease 0.2s forwards;
}

.building-card:nth-child(3) {
    animation: slideInUp 0.6s ease 0.3s forwards;
}

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

.building-header {
    display: flex;
    justify-content: space-between;
    align-items: start;
    margin-bottom: 1.5rem;
}

.building-card h3 {
    font-size: 1.5rem;
    color: var(--text-primary);
    margin-bottom: 0.75rem;
    font-weight: 600;
    line-height: 1.4;
}

.status-badge {
    display: inline-block;
    padding: 6px 14px;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 400;
    white-space: nowrap;
    background-color: var(--dark-secondary);
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
}

.progress-bar {
    width: 100%;
    height: 4px;
    background-color: var(--dark-secondary);
    border-radius: 2px;
    margin: 1.5rem 0;
    overflow: hidden;
    border: 1px solid var(--border-color);
}

.progress-fill {
    height: 100%;
    background-color: var(--text-primary);
    border-radius: 2px;
    transition: width 0.6s ease;
}

.building-description {
    color: var(--text-secondary);
    margin-bottom: 2rem;
    line-height: 1.8;
    font-size: 1rem;
}

.building-technologies {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
}

.building-tech-tag {
    background-color: var(--dark-secondary);
    color: var(--text-secondary);
    padding: 6px 12px;
    border-radius: 4px;
    font-size: 0.85rem;
    font-weight: 400;
    border: 1px solid var(--border-color);
}

.building-timeline {
    color: var(--text-secondary);
    font-size: 0.95rem;
    font-weight: 400;
}

/* Skills Section */
.skills {
    padding: 8rem 0;
    background-color: var(--dark-secondary);
}

.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 3rem;
    max-width: 1000px;
    margin: 0 auto;
}

.skill-category {
    background: var(--dark-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 2.5rem;
    transition: var(--transition);
    opacity: 0;
    transform: translateY(20px);
}

.skill-category:nth-child(1) {
    animation: slideInUp 0.6s ease 0.1s forwards;
}

.skill-category:nth-child(2) {
    animation: slideInUp 0.6s ease 0.2s forwards;
}

.skill-category:nth-child(3) {
    animation: slideInUp 0.6s ease 0.3s forwards;
}

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

.skill-category h3 {
    color: var(--text-primary);
    font-size: 1.3rem;
    margin-bottom: 2rem;
    font-weight: 600;
}

.skill-category ul {
    list-style: none;
}

.skill-category li {
    color: var(--text-secondary);
    padding: 0.9rem 0;
    border-bottom: 1px solid var(--border-color);
    font-size: 1rem;
}

.skill-category li:last-child {
    border-bottom: none;
}

/* Contact Section */
.contact {
    padding: 8rem 0;
    text-align: center;
    background-color: var(--dark-bg);
}

.contact-content {
    max-width: 800px;
    margin: 0 auto;
}

.contact-content > p {
    font-size: 1.2rem;
    color: var(--text-secondary);
    margin-bottom: 3rem;
    line-height: 1.8;
}

.contact-links {
    display: flex;
    justify-content: center;
    gap: 2rem;
    flex-wrap: wrap;
}

.contact-link {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 14px 24px;
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-primary);
    text-decoration: none;
    transition: var(--transition);
    font-weight: 400;
    font-size: 1rem;
}

.contact-link:hover {
    border-color: var(--text-primary);
    background-color: var(--dark-secondary);
}

.contact-link .icon {
    font-size: 1.2rem;
}

/* Footer */
.footer {
    background-color: var(--dark-bg);
    border-top: 1px solid var(--border-color);
    padding: 3rem 0;
    text-align: center;
    color: var(--text-secondary);
}

/* Pagination */
.pagination {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 0.5rem;
    margin-top: 4rem;
    flex-wrap: wrap;
}

.page-btn {
    background: var(--dark-bg);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.6rem 1rem;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: var(--transition);
    min-width: 40px;
    text-align: center;
    font-family: inherit;
}

.page-btn:hover:not(:disabled) {
    border-color: var(--text-primary);
    color: var(--text-primary);
    background-color: var(--dark-secondary);
}

.page-btn:disabled {
    opacity: 0.3;
    cursor: not-allowed;
}

.page-active {
    background-color: var(--text-primary);
    color: var(--dark-bg);
    border-color: var(--text-primary);
}

.page-active:hover {
    background-color: var(--text-primary) !important;
    color: var(--dark-bg) !important;
}

.page-nav {
    font-weight: 500;
}

/* Project Link Button */
.project-link-btn {
    background: none;
    border: none;
    cursor: pointer;
    font-family: inherit;
    font-size: 1rem;
    padding: 0;
    text-align: left;
}

/* Modal Overlay */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.7);
    z-index: 2000;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 2rem;
    opacity: 0;
    transition: opacity 0.3s ease;
    overflow-y: auto;
}

.modal-overlay.modal-active {
    opacity: 1;
}

.modal-content {
    background: var(--dark-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    max-width: 700px;
    width: 100%;
    padding: 2.5rem;
    position: relative;
    transform: scale(0.95);
    transition: transform 0.3s ease;
    max-height: 90vh;
    overflow-y: auto;
}

.modal-active .modal-content {
    transform: scale(1);
}

.modal-close {
    position: absolute;
    top: 1rem;
    right: 1.5rem;
    background: none;
    border: none;
    color: var(--text-secondary);
    font-size: 2rem;
    cursor: pointer;
    transition: var(--transition);
    line-height: 1;
    padding: 0;
    font-family: inherit;
}

.modal-close:hover {
    color: var(--text-primary);
}

.modal-header {
    margin-bottom: 1.5rem;
    padding-right: 2rem;
}

.modal-header h2 {
    font-size: 1.8rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
    line-height: 1.3;
}

.modal-category {
    color: var(--text-secondary);
    font-size: 0.85rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.modal-video {
    position: relative;
    width: 100%;
    padding-bottom: 56.25%;
    margin-bottom: 2rem;
    border-radius: 8px;
    overflow: hidden;
    background-color: var(--dark-secondary);
}

.modal-video iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border-radius: 8px;
}

.modal-body {
    margin-bottom: 1.5rem;
}

.modal-description {
    color: var(--text-secondary);
    line-height: 1.9;
    font-size: 1.05rem;
}

.modal-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-bottom: 2rem;
}

.modal-links {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
    border-top: 1px solid var(--border-color);
    padding-top: 1.5rem;
}

.modal-link {
    display: inline-flex;
    align-items: center;
    padding: 10px 20px;
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-primary);
    text-decoration: none;
    transition: var(--transition);
    font-weight: 500;
    font-size: 0.95rem;
}

.modal-link:hover {
    border-color: var(--text-primary);
    background-color: var(--dark-secondary);
    transform: translateY(-1px);
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 0 24px;
    }

    .navbar .container {
        padding: 1.25rem 24px;
    }

    .nav-menu {
        display: none;
    }

    .nav-menu.active {
        display: flex;
        flex-direction: column;
        position: absolute;
        top: 70px;
        left: 0;
        right: 0;
        background-color: var(--dark-bg);
        padding: 1.5rem 24px;
        gap: 1.5rem;
        border-bottom: 1px solid var(--border-color);
    }

    .hamburger {
        display: flex;
    }

    .hamburger.active span:nth-child(1) {
        transform: rotate(-45deg) translate(-7px, 6px);
    }

    .hamburger.active span:nth-child(2) {
        opacity: 0;
    }

    .hamburger.active span:nth-child(3) {
        transform: rotate(45deg) translate(-7px, -6px);
    }

    .hero-title {
        font-size: 2.5rem;
        letter-spacing: -1px;
    }

    .hero-subtitle {
        font-size: 1.2rem;
    }

    .section-title {
        font-size: 2.2rem;
    }

    .projects-grid,
    .research-grid,
    .building-container {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    .skills-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    .hero,
    .about,
    .research,
    .projects,
    .building,
    .skills,
    .contact {
        padding: 5rem 0;
    }

    .btn {
        width: 100%;
    }

    .contact-links {
        flex-direction: column;
    }

    .contact-link {
        width: 100%;
        justify-content: center;
    }

    .nav-controls {
        gap: 0.75rem;
    }

    .theme-toggle,
    .language-toggle {
        padding: 0.45rem 0.75rem;
        font-size: 0.85rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 20px;
    }

    .navbar .container {
        padding: 1rem 20px;
    }

    .hero-title {
        font-size: 2rem;
    }

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

    .hero-description {
        font-size: 1rem;
    }

    .section-title {
        font-size: 1.8rem;
    }

    .section-description {
        font-size: 1rem;
    }

    .research-card,
    .project-card,
    .building-card,
    .skill-category {
        padding: 2rem;
    }

    .building-header {
        flex-direction: column;
        gap: 1rem;
    }

    .status-badge {
        width: 100%;
        text-align: center;
    }

    .modal-overlay {
        padding: 1rem;
    }

    .modal-content {
        padding: 1.5rem;
    }

    .modal-header h2 {
        font-size: 1.4rem;
    }

    .modal-links {
        flex-direction: column;
    }

    .modal-link {
        width: 100%;
        justify-content: center;
    }

    .modal-research {
        max-width: 100%;
    }

    .modal-research .modal-description {
        font-size: 0.95rem;
    }

    .pagination {
        gap: 0.35rem;
    }

    .page-btn {
        padding: 0.5rem 0.8rem;
        font-size: 0.85rem;
        min-width: 36px;
    }
}