/* ============================================
 * Personal Homepage - Style
 * Version: v2.0
 * Author: Hunpyo Ju
 * Date: 2025-12-15
 * ============================================ */

/* ============================================
 * CSS Variables
 * ============================================ */
:root {
    /* Colors - Light Mode */
    --bg-main: #f5f5f7;
    --bg-section: #ffffff;
    --color-primary: #007AFF;
    --color-primary-light: #5AC8FA;
    --color-text: #1d1d1f;
    --color-text-secondary: #6e6e73;
    --color-border: #d2d2d7;

    /* Typography */
    --font-heading: 'Playfair Display', Georgia, serif;
    --font-body: 'Noto Sans KR', -apple-system, BlinkMacSystemFont, sans-serif;

    /* Spacing */
    --section-padding: 120px;
    --container-width: 1200px;
    --nav-height: 60px;

    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-body);
    background-color: var(--bg-main);
    color: var(--color-text);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Content Protection */
body.protected {
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
}

body.protected img {
    pointer-events: none;
    -webkit-user-drag: none;
}

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

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

img, video {
    max-width: 100%;
    height: auto;
    display: block;
}

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

h1 {
    font-size: clamp(2.5rem, 5vw, 4rem);
    letter-spacing: -0.02em;
}

h1.page-title {
    font-size: clamp(2.25rem, 4.5vw, 3.25rem);
}

h2 {
    font-size: clamp(1.75rem, 3.5vw, 2.25rem);
    letter-spacing: -0.01em;
}

h3 {
    font-size: clamp(1.5rem, 3vw, 2rem);
}

.section-label {
    font-family: var(--font-body);
    font-size: 0.875rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-primary);
    margin-bottom: 1rem;
}

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

.text-large {
    font-size: 1.25rem;
    line-height: 1.8;
}

/* Acronym Styling - ISSAD */
.acronym-letter {
    color: var(--color-primary);
}

/* ============================================
 * Layout
 * ============================================ */
.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 24px;
}

.section {
    padding: var(--section-padding) 0;
}

.section-white {
    background-color: var(--bg-section);
}

.section-gray {
    background-color: var(--bg-main);
}

/* ============================================
 * Navigation
 * ============================================ */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--nav-height);
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--color-border);
    z-index: 1000;
    transition: all var(--transition-normal);
}

.nav-container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 24px;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo {
    font-family: var(--font-heading);
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-text);
}

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

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

.nav-link {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-text-secondary);
    padding-bottom: 0.25rem;
    position: relative;
    display: inline-block;
}

.nav-link:hover,
.nav-link.active {
    color: var(--color-text);
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--color-primary);
    transition: width var(--transition-normal);
}

.nav-link:hover::after,
.nav-link.active::after {
    width: 100%;
}

/* Mobile Menu Toggle */
.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
    padding: 5px;
}

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

/* ============================================
 * Hero Section
 * ============================================ */
.hero {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: calc(var(--nav-height) + 60px) 24px 60px;
    background: var(--bg-section);
    position: relative;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: url('../assets/images/hero/Background.jpg');
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    opacity: 0.7;
    pointer-events: none;
}

.hero-content {
    max-width: 900px;
    position: relative;
    z-index: 1;
}

.hero-title {
    margin-bottom: 1.5rem;
    opacity: 0;
    transform: translateY(30px);
    text-shadow: 0 0 12px rgba(255, 255, 255, 0.8), 0 0 25px rgba(255, 255, 255, 0.5);
}

.hero-subtitle {
    font-size: clamp(1.125rem, 2vw, 1.5rem);
    color: var(--color-text);
    margin-bottom: 2rem;
    opacity: 0;
    transform: translateY(30px);
    text-shadow: 0 0 15px rgba(255, 255, 255, 0.8);
}

.hero-description {
    font-size: 1.125rem;
    color: var(--color-text);
    max-width: 700px;
    margin: 0 auto 3rem;
    opacity: 0;
    transform: translateY(30px);
    text-shadow: 0 0 15px rgba(255, 255, 255, 0.8);
}

.hero-cta {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
    opacity: 0;
    transform: translateY(30px);
}

/* ============================================
 * Buttons
 * ============================================ */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.875rem 1.75rem;
    font-size: 1rem;
    font-weight: 500;
    border-radius: 50px;
    cursor: pointer;
    transition: all var(--transition-normal);
    border: none;
}

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

.btn-primary:hover {
    background: #0056b3;
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 10px 30px rgba(0, 122, 255, 0.3);
}

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

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

/* ============================================
 * Stats Section
 * ============================================ */
.stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    text-align: center;
}

.stat-item {
    padding: 2rem;
}

.stat-number {
    font-family: var(--font-heading);
    font-size: clamp(2.5rem, 5vw, 4rem);
    font-weight: 700;
    color: var(--color-primary);
    line-height: 1;
    margin-bottom: 0.5rem;
}

.stat-label {
    font-size: 1rem;
    color: var(--color-text-secondary);
}

/* ============================================
 * Research Cards
 * ============================================ */
.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
}

.research-card {
    background: var(--bg-section);
    border-radius: 16px;
    overflow: hidden;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.05);
    transition: all var(--transition-normal);
}

.research-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
}

.research-card-media {
    position: relative;
    aspect-ratio: 16/10;
    overflow: hidden;
    background: var(--bg-main);
}

.research-card-media img,
.research-card-media video {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.research-card-content {
    padding: 1.5rem;
}

.research-card-title {
    font-size: 1.25rem;
    margin-bottom: 0.75rem;
}

.research-card-description {
    font-size: 0.9375rem;
    color: var(--color-text-secondary);
    margin-bottom: 1rem;
}

.research-card-meta {
    font-size: 0.8125rem;
    color: var(--color-primary);
    font-weight: 500;
}

/* ============================================
 * Research Detail (Full Width Sections)
 * ============================================ */
.research-section {
    padding: 80px 0;
    border-bottom: 1px solid var(--color-border);
}

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

.research-header {
    text-align: center;
    margin-bottom: 3rem;
}

.research-header h2 {
    margin-bottom: 1rem;
}

.research-header p {
    font-size: 1.125rem;
    color: var(--color-text-secondary);
    max-width: 800px;
    margin: 0 auto;
}

.research-media-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem;
}

.research-media-item {
    border-radius: 12px;
    overflow: hidden;
    background: var(--bg-main);
}

.research-media-item video {
    width: 100%;
    display: block;
}

/* Side by side layout for Virtual/Real */
.media-side-by-side {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

.media-side-by-side .media-item {
    position: relative;
}

.media-side-by-side .media-label {
    position: absolute;
    bottom: 12px;
    left: 12px;
    background: rgba(0, 0, 0, 0.7);
    color: white;
    padding: 4px 12px;
    border-radius: 4px;
    font-size: 0.75rem;
    font-weight: 600;
}

/* ============================================
 * Publications
 * ============================================ */
.publication-list {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.publication-item {
    display: grid;
    grid-template-columns: 120px 1fr;
    gap: 1.5rem;
    padding: 1.5rem;
    background: var(--bg-section);
    border-radius: 12px;
    transition: all var(--transition-normal);
}

.publication-item:hover {
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
}

.publication-item.featured {
    border: 2px solid var(--color-primary);
}

.publication-image {
    width: 120px;
    min-height: 80px;
    border-radius: 8px;
    overflow: hidden;
    background: var(--bg-main);
    flex-shrink: 0;
    display: flex;
    align-items: center;
    justify-content: center;
}

.publication-image img {
    width: 100%;
    height: auto;
    object-fit: contain;
}

.publication-image.placeholder {
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text-secondary);
    font-size: 0.75rem;
}

.publication-content {
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.publication-badge {
    display: inline-block;
    background: var(--color-primary);
    color: white;
    font-size: 0.6875rem;
    font-weight: 600;
    padding: 2px 8px;
    border-radius: 4px;
    margin-bottom: 0.5rem;
    width: fit-content;
}

.publication-title {
    font-family: var(--font-body);
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    line-height: 1.4;
}

.publication-journal {
    font-size: 0.875rem;
    color: var(--color-primary);
    font-style: italic;
    margin-bottom: 0.25rem;
}

.publication-year {
    font-size: 0.8125rem;
    color: var(--color-text-secondary);
}

.publication-link {
    display: inline-block;
    margin-top: 0.5rem;
    font-size: 0.8125rem;
    font-weight: 500;
    color: var(--color-primary);
    text-decoration: none;
    transition: all var(--transition-fast);
}

.publication-link:hover {
    color: var(--color-primary-light);
}

/* ============================================
 * Publications V2 (Numbered, Large ToC)
 * ============================================ */
.publication-list-v2 {
    display: flex;
    flex-direction: column;
    gap: 0;
}

.pub-item {
    display: grid;
    grid-template-columns: 320px 1fr;
    gap: 1.5rem;
    padding: 1.5rem 0;
    border-bottom: 1px solid var(--color-border);
    align-items: start;
}

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

.pub-item.featured {
    background: linear-gradient(90deg, rgba(0, 122, 255, 0.05) 0%, transparent 100%);
    margin: 0 -1rem;
    padding: 1.5rem 1rem;
    border-radius: 8px;
}

.pub-number {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    background: var(--color-text);
    color: white;
    font-size: 0.8125rem;
    font-weight: 600;
    border-radius: 50%;
    flex-shrink: 0;
}

.pub-image {
    width: 320px;
    background: var(--bg-main);
    border-radius: 8px;
    overflow: hidden;
    flex-shrink: 0;
}

.pub-image img {
    width: 100%;
    height: auto;
    display: block;
}

.pub-image.placeholder {
    height: 180px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text-secondary);
    font-size: 0.875rem;
    font-weight: 500;
}

.pub-content {
    display: flex;
    flex-direction: column;
    justify-content: flex-start;
    padding-top: 0.25rem;
}

.pub-badge {
    display: inline-block;
    background: var(--color-primary);
    color: white;
    font-size: 0.6875rem;
    font-weight: 600;
    padding: 3px 10px;
    border-radius: 4px;
    margin-bottom: 0.75rem;
    width: fit-content;
}

.pub-title {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    line-height: 1.5;
}

.pub-journal {
    font-size: 0.9375rem;
    color: var(--color-primary);
    font-style: italic;
    margin-bottom: 0.25rem;
}

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

.pub-link {
    display: inline-block;
    margin-top: 0.75rem;
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-primary);
    text-decoration: none;
    transition: all var(--transition-fast);
}

.pub-link:hover {
    color: var(--color-primary-light);
}

/* ============================================
 * Cover Gallery
 * ============================================ */
.cover-gallery {
    display: flex;
    justify-content: center;
    align-items: flex-start;
    gap: 2rem;
    flex-wrap: wrap;
}

.cover-item {
    text-align: center;
}

.cover-item img {
    height: 380px;
    width: auto;
    border-radius: 12px;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.15);
    transition: transform var(--transition-normal);
}

.cover-item img:hover {
    transform: scale(1.02);
}

.cover-caption {
    margin-top: 1rem;
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    font-style: italic;
}

/* ============================================
 * Profile Card
 * ============================================ */
.profile-card {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 3rem;
    align-items: start;
    padding: 3rem;
    background: var(--bg-section);
    border-radius: 20px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.05);
}

.profile-image {
    height: 210px;
    border-radius: 16px;
    overflow: hidden;
    background: var(--bg-main);
}

.profile-image img {
    height: 100%;
    width: auto;
}

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

.profile-title {
    font-size: 1.25rem;
    color: var(--color-primary);
    margin-bottom: 0.5rem;
}

.profile-affiliation {
    font-size: 1rem;
    color: var(--color-text-secondary);
    margin-bottom: 1.5rem;
}

.profile-links {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

/* ============================================
 * Timeline
 * ============================================ */
.timeline {
    position: relative;
    padding-left: 2rem;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--color-border);
}

.timeline-item {
    position: relative;
    padding-bottom: 2rem;
}

.timeline-item:last-child {
    padding-bottom: 0;
}

.timeline-item::before {
    content: '';
    position: absolute;
    left: -2rem;
    top: 0.5rem;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--color-primary);
    transform: translateX(-5px);
}

.timeline-year {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: 0.25rem;
}

.timeline-title {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.timeline-subtitle {
    font-size: 0.9375rem;
    color: var(--color-text-secondary);
}

/* ============================================
 * Contact Card
 * ============================================ */
.contact-card {
    max-width: 600px;
    margin: 0 auto;
    padding: 3rem;
    background: var(--bg-section);
    border-radius: 20px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.05);
    text-align: center;
}

.contact-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem 0;
    border-bottom: 1px solid var(--color-border);
    text-align: left;
}

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

.contact-icon {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-main);
    border-radius: 10px;
    color: var(--color-primary);
    flex-shrink: 0;
}

.contact-label {
    font-size: 0.75rem;
    color: var(--color-text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.contact-value {
    font-size: 1rem;
    font-weight: 500;
}

.copy-btn {
    margin-left: auto;
    padding: 0.5rem 1rem;
    font-size: 0.75rem;
    background: var(--bg-main);
    border: 1px solid var(--color-border);
    border-radius: 6px;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.copy-btn:hover {
    background: var(--color-primary);
    color: white;
    border-color: var(--color-primary);
}

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

.footer-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
}

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

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

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

.footer-copyright {
    font-size: 0.8125rem;
    color: var(--color-text-secondary);
}

/* ============================================
 * Animations
 * ============================================ */
.fade-up {
    opacity: 0;
    transform: translateY(40px);
}

.fade-up.animated {
    opacity: 1;
    transform: translateY(0);
    transition: all 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ============================================
 * Responsive
 * ============================================ */
@media (max-width: 1024px) {
    :root {
        --section-padding: 80px;
    }

    .profile-card {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .profile-image {
        margin: 0 auto;
    }

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

@media (max-width: 768px) {
    :root {
        --section-padding: 60px;
        --nav-height: 56px;
    }

    /* Mobile Navigation */
    .nav-menu {
        position: fixed;
        top: var(--nav-height);
        left: 0;
        right: 0;
        background: rgba(255, 255, 255, 0.98);
        backdrop-filter: blur(20px);
        flex-direction: column;
        padding: 1.5rem;
        gap: 0;
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all var(--transition-normal);
        border-bottom: 1px solid var(--color-border);
    }

    .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

    .nav-menu li {
        width: 100%;
    }

    .nav-link {
        display: block;
        width: 100%;
        padding: 1rem 0;
        border-bottom: 1px solid var(--color-border);
        text-align: left;
    }

    .nav-link::after {
        display: none;
    }

    .nav-link.active {
        color: var(--color-primary);
    }

    .nav-toggle {
        display: flex;
    }

    /* Research */
    .research-grid {
        grid-template-columns: 1fr;
    }

    .media-side-by-side {
        grid-template-columns: 1fr;
    }

    /* Publications */
    .publication-item {
        grid-template-columns: 1fr;
    }

    .publication-image {
        width: 100%;
        height: 200px;
    }

    /* Publications V2 */
    .pub-item {
        grid-template-columns: 1fr;
        gap: 1rem;
    }

    .pub-image {
        width: 100%;
    }

    /* Hero */
    .hero {
        padding-top: calc(var(--nav-height) + 40px);
    }

    .hero-cta {
        flex-direction: column;
        align-items: center;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 16px;
    }

    .stats {
        grid-template-columns: 1fr 1fr;
    }

    .profile-card {
        padding: 1.5rem;
    }

    .contact-card {
        padding: 1.5rem;
    }
}