/* ==========================================
   Dongho Park - Academic Website
   Modern Impact Style
   ========================================== */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&display=swap');

:root {
    --primary-color: #0066cc;
    --primary-dark: #0052a3;
    --primary-light: #3385d6;
    --text-color: #111111;
    --text-light: #555555;
    --bg-color: #ffffff;
    --bg-light: #f5f5f7;
    --border-color: #d2d2d7;
    --accent-color: #0066cc;
    --max-width: 1200px;
    --font-main: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-main);
    font-size: 17px;
    line-height: 1.7;
    color: var(--text-color);
    background-color: var(--bg-color);
    -webkit-font-smoothing: antialiased;
}

a {
    color: var(--primary-color);
    text-decoration: none;
    transition: all 0.2s ease;
}

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

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-main);
    color: var(--text-color);
    font-weight: 700;
    line-height: 1.2;
    letter-spacing: -0.02em;
}

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

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 60px;
}

.nav-logo {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--text-color);
    letter-spacing: -0.01em;
}

.nav-logo:hover {
    color: var(--primary-color);
}

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

.nav-link {
    color: var(--text-color);
    font-weight: 500;
    padding: 0.5rem 0;
    border-bottom: 2px solid transparent;
}

.nav-link:hover,
.nav-link.active {
    color: var(--primary-color);
    text-decoration: none;
    border-bottom-color: var(--primary-color);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.nav-toggle span {
    width: 24px;
    height: 2px;
    background: var(--text-color);
    transition: 0.3s;
}

/* Main Content */
main {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 80px 2rem 4rem;
}

section {
    margin-bottom: 4rem;
}

section h2 {
    font-size: 1.8rem;
    font-weight: 800;
    margin-bottom: 2rem;
    color: var(--text-color);
    letter-spacing: -0.03em;
}

/* Hero Section */
.hero {
    padding: 5rem 0;
}

.hero-content {
    display: flex;
    gap: 4rem;
    align-items: center;
}

.hero-text {
    flex: 1;
}

.hero h1 {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: 0.75rem;
    color: var(--text-color);
    letter-spacing: -0.04em;
}

.subtitle {
    font-size: 1.3rem;
    color: var(--text-light);
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.affiliation {
    margin-bottom: 2rem;
    font-size: 1.1rem;
}

.hero-links {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
}

.hero-image {
    flex-shrink: 0;
}

.profile-placeholder {
    width: 320px;
    height: 320px;
    border-radius: 8px;
    background: var(--bg-light);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-light);
    font-size: 0.9rem;
}

.profile-placeholder img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: 8px;
}

/* Profile Carousel */
.profile-carousel {
    position: relative;
    width: 320px;
    height: 320px;
}

.carousel-container {
    width: 100%;
    height: 100%;
    position: relative;
    border-radius: 8px;
    overflow: hidden;
}

.carousel-slide {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    transition: opacity 0.5s ease-in-out;
}

.carousel-slide.active {
    opacity: 1;
}

.carousel-slide img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: 8px;
}

.carousel-caption {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    background: rgba(0, 0, 0, 0.7);
    color: white;
    padding: 0.75rem;
    font-size: 0.85rem;
    text-align: center;
    opacity: 0;
    transition: opacity 0.3s ease;
    border-radius: 0 0 8px 8px;
}

.carousel-slide:hover .carousel-caption,
.profile-carousel:hover .carousel-caption {
    opacity: 1;
}

.carousel-arrow {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    background: rgba(255, 255, 255, 0.8);
    border: none;
    width: 32px;
    height: 32px;
    border-radius: 50%;
    cursor: pointer;
    font-size: 14px;
    color: var(--text-color);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: opacity 0.3s ease, background 0.3s ease;
    z-index: 10;
}

.profile-carousel:hover .carousel-arrow {
    opacity: 1;
}

.carousel-arrow:hover {
    background: rgba(255, 255, 255, 1);
}

.carousel-prev {
    left: 8px;
}

.carousel-next {
    right: 8px;
}

.carousel-dots {
    position: absolute;
    bottom: -24px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    gap: 8px;
}

.carousel-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--border-color);
    cursor: pointer;
    transition: background 0.3s ease;
}

.carousel-dot:hover,
.carousel-dot.active {
    background: var(--primary-color);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: 50px;
    font-weight: 600;
    font-size: 0.95rem;
    transition: all 0.3s ease;
}

.btn:hover {
    transform: translateY(-1px);
}

.btn-primary {
    background: var(--primary-color);
    color: white;
    box-shadow: 0 4px 14px rgba(0, 102, 204, 0.25);
}

.btn-primary:hover {
    background: var(--primary-dark);
    color: white;
    box-shadow: 0 6px 20px rgba(0, 102, 204, 0.35);
}

.btn-secondary {
    background: var(--bg-light);
    color: var(--text-color);
    border: none;
}

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

/* About Section */
.about p {
    margin-bottom: 1rem;
}

.about p:last-child {
    margin-bottom: 0;
}

/* Research Highlights - Vertical Layout */
.research-highlights {
    margin-bottom: 4rem;
}

.highlight-row {
    display: flex;
    gap: 3rem;
    align-items: center;
    padding: 2.5rem 0;
    border-bottom: 1px solid var(--border-color);
}

.highlight-row:last-child {
    border-bottom: none;
}

.highlight-row.reverse {
    flex-direction: row-reverse;
}

.highlight-text {
    flex: 1;
}

.highlight-text h3 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-color);
    letter-spacing: -0.02em;
}

.highlight-text p {
    color: var(--text-light);
    font-size: 1.05rem;
    line-height: 1.7;
    margin-bottom: 1.25rem;
}

.highlight-media {
    flex-shrink: 0;
    width: 480px;
    border-radius: 16px;
    overflow: hidden;
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.12);
}

.highlight-media video,
.highlight-media img {
    width: 100%;
    height: auto;
    display: block;
}

.card-link {
    display: inline-flex;
    align-items: center;
    font-size: 1rem;
    font-weight: 600;
    color: var(--primary-color);
    transition: all 0.2s ease;
}

.card-link:hover {
    color: var(--primary-dark);
    gap: 0.5rem;
}

/* News */
.news-list {
    list-style: none;
}

.news-list li {
    display: flex;
    gap: 1.5rem;
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--border-color);
}

.news-list li:last-child {
    border-bottom: none;
}

.news-date {
    flex-shrink: 0;
    width: 80px;
    color: var(--primary-color);
    font-weight: 600;
    font-size: 0.9rem;
}

/* Publications */
.pub-list {
    margin-bottom: 1.5rem;
}

.pub-item {
    padding: 1rem 0;
    border-bottom: 1px solid var(--border-color);
}

.pub-item:last-child {
    border-bottom: none;
}

.pub-title {
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: 0.25rem;
}

.pub-authors {
    font-size: 0.95rem;
    color: var(--text-light);
    margin-bottom: 0.25rem;
}

.pub-venue {
    font-size: 0.9rem;
    color: var(--text-light);
}

.pub-highlight {
    color: var(--accent-color);
    font-weight: 600;
}

.pub-links {
    margin-top: 0.5rem;
    display: flex;
    gap: 1rem;
}

.pub-links a {
    font-size: 0.85rem;
    font-weight: 500;
}

.pub-link {
    font-size: 0.85rem;
    font-weight: 500;
    margin-left: 0.25rem;
}

/* Publications Page Specific */
.pub-section {
    margin-bottom: 3rem;
}

.pub-section h3 {
    font-size: 1.2rem;
    margin-bottom: 1rem;
    color: var(--text-color);
}

.pub-number {
    color: var(--primary-color);
    font-weight: 600;
    margin-right: 0.5rem;
}

/* Research Page */
.research-section {
    margin-bottom: 3rem;
    padding-bottom: 2rem;
    border-bottom: 1px solid var(--border-color);
}

.research-section:last-child {
    border-bottom: none;
}

.research-section h3 {
    font-size: 1.6rem;
    font-weight: 700;
    margin-bottom: 1.25rem;
    color: var(--text-color);
    letter-spacing: -0.02em;
}

.research-content {
    display: flex;
    gap: 2rem;
    align-items: flex-start;
}

.research-content.reverse {
    flex-direction: row-reverse;
}

.research-text {
    flex: 1;
}

.research-text p {
    margin-bottom: 1rem;
}

.research-text ul {
    margin-bottom: 1rem;
}

.research-media {
    flex-shrink: 0;
    width: 520px;
}

.video-container {
    position: relative;
    width: 100%;
    padding-bottom: 56.25%; /* 16:9 aspect ratio */
    background: transparent;
    border-radius: 8px;
    overflow: hidden;
}

.video-container iframe,
.video-container video {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

.video-placeholder {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-light);
    font-size: 0.9rem;
    border: 2px dashed var(--border-color);
    border-radius: 8px;
}

.image-container {
    width: 100%;
    border-radius: 8px;
    overflow: hidden;
    background: var(--bg-light);
}

.image-container img {
    width: 100%;
    height: auto;
    display: block;
    border-radius: 8px;
}

/* CV Page */
.cv-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

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

.pdf-viewer {
    width: 100%;
    height: 800px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
}

.cv-links {
    margin-top: 1.5rem;
    padding: 1rem;
    background: var(--bg-light);
    border-radius: 8px;
}

.cv-links h3 {
    font-size: 1rem;
    margin-bottom: 0.75rem;
}

.cv-links p {
    font-size: 0.9rem;
    color: var(--text-light);
}

/* Blog Page */
.blog-list {
    list-style: none;
}

.blog-item {
    padding: 1.5rem 0;
    border-bottom: 1px solid var(--border-color);
}

.blog-item:last-child {
    border-bottom: none;
}

.blog-date {
    font-size: 0.85rem;
    color: var(--text-light);
    margin-bottom: 0.25rem;
}

.blog-title {
    font-size: 1.2rem;
    margin-bottom: 0.5rem;
}

.blog-title a {
    color: var(--text-color);
}

.blog-title a:hover {
    color: var(--primary-color);
}

.blog-excerpt {
    color: var(--text-light);
    font-size: 0.95rem;
}

.blog-coming-soon {
    text-align: center;
    padding: 3rem;
    background: var(--bg-light);
    border-radius: 8px;
    color: var(--text-light);
}

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

.footer-content {
    max-width: var(--max-width);
    margin: 0 auto;
    text-align: center;
    font-size: 0.9rem;
    color: var(--text-light);
}

.footer-content p {
    margin-bottom: 0.5rem;
}

.footer-content a {
    color: var(--text-light);
}

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

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        top: 60px;
        left: 0;
        right: 0;
        background: var(--bg-color);
        flex-direction: column;
        padding: 1rem 2rem;
        gap: 0;
        border-bottom: 1px solid var(--border-color);
        display: none;
    }

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

    .nav-menu li {
        border-bottom: 1px solid var(--border-color);
    }

    .nav-menu li:last-child {
        border-bottom: none;
    }

    .nav-link {
        display: block;
        padding: 0.75rem 0;
        border-bottom: none;
    }

    .nav-link:hover,
    .nav-link.active {
        border-bottom: none;
    }

    .nav-toggle {
        display: flex;
    }

    .hero-content {
        flex-direction: column-reverse;
        text-align: center;
    }

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

    .profile-placeholder {
        width: 200px;
        height: 200px;
    }

    .profile-carousel {
        width: 200px;
        height: 200px;
    }

    .carousel-arrow {
        width: 28px;
        height: 28px;
        font-size: 12px;
    }

    .news-list li {
        flex-direction: column;
        gap: 0.25rem;
    }

    .news-date {
        width: auto;
    }

    .research-content {
        flex-direction: column;
    }

    .research-media {
        width: 100%;
    }

    .highlight-row,
    .highlight-row.reverse {
        flex-direction: column;
        gap: 1.5rem;
        padding: 2rem 0;
    }

    .highlight-media {
        width: 100%;
    }

    .cv-header {
        flex-direction: column;
        gap: 1rem;
        align-items: flex-start;
    }

    .pdf-viewer {
        height: 500px;
    }
}

@media (max-width: 480px) {
    main {
        padding: 70px 1rem 2rem;
    }

    .hero h1 {
        font-size: 2rem;
    }

    section h2 {
        font-size: 1.3rem;
    }
}