/* ============================================
   LM Research Lab - Main Stylesheet
   Professional Academic Design
   ============================================ */

/* CSS Custom Properties (Variables) */
:root {
    /* Color Palette - Konkuk University Green Theme */
    --primary-color: #0e664f;
    --primary-light: #148c6b;
    --primary-dark: #0a4a3a;
    --secondary-color: #1a8f6e;
    --accent-color: #4db897;
    
    /* Neutral Colors */
    --text-primary: #1a202c;
    --text-secondary: #4a5568;
    --text-light: #718096;
    --bg-primary: #ffffff;
    --bg-secondary: #f7fafc;
    --bg-tertiary: #edf2f7;
    --border-color: #e2e8f0;
    
    /* Typography */
    --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-heading: 'Playfair Display', Georgia, serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    
    /* Layout */
    --max-width: 1200px;
    --header-height: 70px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.15);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 300ms ease;
    
    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-full: 9999px;
}

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

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

body {
    font-family: var(--font-primary);
    font-size: 1rem;
    line-height: 1.7;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: 700;
    line-height: 1.3;
    color: var(--primary-color);
    margin-bottom: var(--spacing-md);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }
h5 { font-size: 1.125rem; }
h6 { font-size: 1rem; }

p {
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
}

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

a:hover, a:focus {
    color: var(--primary-color);
    text-decoration: underline;
}

/* Focus styles for accessibility */
a:focus-visible, button:focus-visible, input:focus-visible {
    outline: 3px solid var(--accent-color);
    outline-offset: 2px;
}

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

ul, ol {
    padding-left: var(--spacing-xl);
    margin-bottom: var(--spacing-md);
}

li {
    margin-bottom: var(--spacing-xs);
}

/* Utility Classes */
.container {
    width: 100%;
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.section {
    padding: var(--spacing-3xl) 0;
}

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

.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* ============================================
   Header & Navigation
   ============================================ */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    transition: box-shadow var(--transition-normal);
}

.header.scrolled {
    box-shadow: var(--shadow-md);
}

.header .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-family: var(--font-heading);
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
}

.logo:hover {
    text-decoration: none;
    color: var(--secondary-color);
}

.logo img {
    height: 55px;
    width: auto;
}

.logo span {
    display: none;
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: var(--spacing-xl);
    list-style: none;
    padding: 0;
    margin: 0;
}

.nav-menu a {
    font-weight: 500;
    color: var(--text-secondary);
    padding: var(--spacing-sm) 0;
    position: relative;
    text-decoration: none;
}

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

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

.nav-menu a:hover,
.nav-menu a.active {
    color: var(--primary-color);
    text-decoration: none;
}

/* Mobile Menu Toggle */
.menu-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--spacing-sm);
}

.menu-toggle span {
    display: block;
    width: 25px;
    height: 2px;
    background-color: var(--primary-color);
    transition: transform var(--transition-fast), opacity var(--transition-fast);
}

.menu-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

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

.menu-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
}

/* Main Content */
main {
    margin-top: var(--header-height);
    min-height: calc(100vh - var(--header-height));
}

/* ============================================
   Hero Section
   ============================================ */
.hero {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-light) 100%);
    color: white;
    padding: var(--spacing-3xl) 0;
    text-align: center;
}

.hero h1 {
    color: white;
    font-size: 3rem;
    margin-bottom: var(--spacing-lg);
}

.hero .subtitle {
    font-size: 1.25rem;
    opacity: 0.9;
    max-width: 700px;
    margin: 0 auto var(--spacing-xl);
    color: rgba(255, 255, 255, 0.9);
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
    flex-wrap: wrap;
}

/* ============================================
   Buttons
   ============================================ */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-xl);
    font-size: 1rem;
    font-weight: 500;
    text-decoration: none;
    border-radius: var(--radius-md);
    border: 2px solid transparent;
    cursor: pointer;
    transition: all var(--transition-fast);
}

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

.btn-primary:hover {
    background-color: var(--primary-color);
    border-color: var(--primary-color);
    color: white;
    text-decoration: none;
}

.btn-secondary {
    background-color: transparent;
    color: white;
    border-color: white;
}

.btn-secondary:hover {
    background-color: white;
    color: var(--primary-color);
    text-decoration: none;
}

.btn-outline {
    background-color: transparent;
    color: var(--secondary-color);
    border-color: var(--secondary-color);
}

.btn-outline:hover {
    background-color: var(--secondary-color);
    color: white;
    text-decoration: none;
}

/* ============================================
   Cards
   ============================================ */
.card {
    background-color: var(--bg-primary);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    overflow: hidden;
    transition: transform var(--transition-normal), box-shadow var(--transition-normal);
}

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

.card-image {
    width: 100%;
    height: 200px;
    object-fit: cover;
    background-color: var(--bg-tertiary);
}

.card-content {
    padding: var(--spacing-lg);
}

.card-title {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-sm);
}

.card-text {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
}

.card-meta {
    font-size: 0.875rem;
    color: var(--text-light);
}

/* ============================================
   Grid Layouts
   ============================================ */
.grid {
    display: grid;
    gap: var(--spacing-xl);
}

.grid-2 {
    grid-template-columns: repeat(2, 1fr);
}

.grid-3 {
    grid-template-columns: repeat(3, 1fr);
}

.grid-4 {
    grid-template-columns: repeat(4, 1fr);
}

/* ============================================
   Section Headers
   ============================================ */
.section-header {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

.section-header h2 {
    position: relative;
    display: inline-block;
    padding-bottom: var(--spacing-md);
}

.section-header h2::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 3px;
    background-color: var(--secondary-color);
}

.section-header p {
    max-width: 600px;
    margin: var(--spacing-md) auto 0;
}

/* ============================================
   Team Member Cards
   ============================================ */
.team-card {
    text-align: center;
    padding: var(--spacing-xl);
}

.team-photo {
    width: 150px;
    height: 150px;
    border-radius: var(--radius-full);
    object-fit: cover;
    margin: 0 auto var(--spacing-lg);
    border: 4px solid var(--bg-tertiary);
}

.team-name {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-xs);
}

.team-role {
    color: var(--secondary-color);
    font-weight: 500;
    margin-bottom: var(--spacing-sm);
}

.team-bio {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
}

.team-links {
    display: flex;
    justify-content: center;
    gap: var(--spacing-md);
}

.team-links a {
    color: var(--text-light);
    font-size: 1.25rem;
    transition: color var(--transition-fast);
}

.team-links a:hover {
    color: var(--secondary-color);
}

/* Empty Team Card (To Be Appointed) */
.team-card-empty {
    opacity: 0.7;
}

.team-photo-placeholder {
    width: 150px;
    height: 150px;
    border-radius: var(--radius-full);
    background: var(--bg-tertiary);
    margin: 0 auto var(--spacing-lg);
    border: 4px dashed var(--text-light);
    display: flex;
    align-items: center;
    justify-content: center;
}

.team-photo-placeholder span {
    font-size: 3rem;
    color: var(--text-light);
    font-weight: 300;
}

/* Professor Section - Vertical Layout */
.professor-section {
    max-width: 800px;
    margin: 0 auto;
}

.professor-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-2xl);
    box-shadow: var(--shadow-md);
    text-align: center;
}

/* Header section */
.professor-header {
    margin-bottom: var(--spacing-xl);
}

.professor-name {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

.professor-role {
    font-size: 1.25rem;
    color: var(--secondary-color);
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
}

.professor-affiliation {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
}

.professor-education {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-bottom: 0;
}

/* Photo section */
.professor-photo-container {
    margin-bottom: var(--spacing-xl);
}

.professor-photo {
    width: 280px;
    height: auto;
    max-height: 350px;
    object-fit: cover;
    object-position: center top;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
}

/* Research Interests */
.professor-research {
    margin-bottom: var(--spacing-xl);
    width: 100%;
}

.professor-research h4,
.professor-awards h4 {
    font-size: 1.1rem;
    color: var(--primary-color);
    margin-bottom: var(--spacing-sm);
    font-weight: 600;
}

.professor-research p {
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Research Highlights specific styling */
.professor-research.highlights {
    text-align: center;
}

.professor-research.highlights h4 {
    text-align: center;
}

.professor-research.highlights p {
    font-size: 0.9rem;
    margin-bottom: var(--spacing-xs);
    text-align: left;
}

/* Awards section */
.professor-awards {
    width: 100%;
    border-top: 1px solid var(--bg-tertiary);
    padding-top: var(--spacing-lg);
}

.awards-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-md);
}

.award-item {
    padding: var(--spacing-sm);
    color: var(--text-secondary);
    font-size: 0.9rem;
    background: var(--bg-tertiary);
    border-radius: var(--radius-sm);
    line-height: 1.5;
    text-align: left;
}

.award-item strong {
    color: var(--text-primary);
    font-weight: 600;
    display: block;
    margin-bottom: var(--spacing-xs);
}

@media (max-width: 992px) {
    .awards-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .professor-photo {
        width: 220px;
        max-height: 280px;
    }

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

/* ============================================
   Publication List
   ============================================ */
.publication-item {
    padding: var(--spacing-xl);
    border-bottom: 1px solid var(--border-color);
}

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

.publication-title {
    font-size: 1.125rem;
    font-family: var(--font-primary);
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: var(--spacing-sm);
}

.publication-authors {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
}

.publication-venue {
    font-style: italic;
    color: var(--text-light);
    margin-bottom: var(--spacing-sm);
}

.publication-links {
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.publication-links a {
    font-size: 0.875rem;
    padding: var(--spacing-xs) var(--spacing-sm);
    background-color: var(--bg-tertiary);
    border-radius: var(--radius-sm);
}

.publication-links a:hover {
    background-color: var(--secondary-color);
    color: white;
    text-decoration: none;
}

.publication-links .coming-soon {
    font-size: 0.875rem;
    padding: var(--spacing-xs) var(--spacing-sm);
    background-color: var(--bg-tertiary);
    border-radius: var(--radius-sm);
    color: var(--text-light);
    font-style: italic;
}

.publication-year {
    display: inline-block;
    background-color: var(--primary-color);
    color: white;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    font-size: 0.75rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
}

/* ============================================
   Research Areas / Features
   ============================================ */
.feature-card {
    padding: var(--spacing-xl);
    text-align: center;
}

.feature-icon {
    width: 64px;
    height: 64px;
    margin: 0 auto var(--spacing-lg);
    background-color: var(--bg-tertiary);
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    color: var(--secondary-color);
}

.feature-title {
    font-size: 1.125rem;
    margin-bottom: var(--spacing-sm);
}

.feature-text {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* ============================================
   Contact Section
   ============================================ */
.contact-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-2xl);
}

.contact-info h3 {
    margin-bottom: var(--spacing-lg);
}

.contact-item {
    display: flex;
    align-items: flex-start;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

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

.contact-details h4 {
    font-size: 1rem;
    margin-bottom: var(--spacing-xs);
}

.contact-details p {
    margin: 0;
    color: var(--text-secondary);
}

.map-container {
    border-radius: var(--radius-lg);
    overflow: hidden;
    height: 100%;
    min-height: 300px;
    background-color: var(--bg-tertiary);
}

.map-container iframe {
    width: 100%;
    height: 100%;
    border: none;
}

/* Social Links */
.social-links {
    display: flex;
    gap: var(--spacing-md);
    margin-top: var(--spacing-lg);
}

.social-links a {
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--bg-tertiary);
    border-radius: var(--radius-full);
    color: var(--text-secondary);
    font-size: 1.25rem;
    transition: all var(--transition-fast);
}

.social-links a:hover {
    background-color: var(--secondary-color);
    color: white;
}

/* ============================================
   Footer
   ============================================ */
.footer {
    background-color: var(--primary-dark);
    color: white;
    padding: var(--spacing-2xl) 0;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--spacing-lg);
}

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

.footer-links {
    display: flex;
    gap: var(--spacing-lg);
    list-style: none;
    padding: 0;
    margin: 0;
}

.footer-links a {
    color: rgba(255, 255, 255, 0.7);
}

.footer-links a:hover {
    color: white;
}

.footer-copyright {
    width: 100%;
    text-align: center;
    padding-top: var(--spacing-lg);
    margin-top: var(--spacing-lg);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.6);
    font-size: 0.875rem;
}

/* ============================================
   Page Headers
   ============================================ */
.page-header {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-light) 100%);
    color: white;
    padding: var(--spacing-2xl) 0;
    text-align: center;
}

.page-header h1 {
    color: white;
    margin-bottom: var(--spacing-sm);
}

.page-header p {
    color: rgba(255, 255, 255, 0.9);
    max-width: 600px;
    margin: 0 auto;
}

/* Breadcrumb */
.breadcrumb {
    display: flex;
    justify-content: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
    font-size: 0.875rem;
}

.breadcrumb a {
    color: rgba(255, 255, 255, 0.7);
}

.breadcrumb a:hover {
    color: white;
}

.breadcrumb span {
    color: rgba(255, 255, 255, 0.5);
}

/* ============================================
   Responsive Design
   ============================================ */
@media (max-width: 1024px) {
    .grid-4 {
        grid-template-columns: repeat(2, 1fr);
    }

    .grid-3 {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    html {
        font-size: 15px;
    }

    h1 { font-size: 2rem; }
    h2 { font-size: 1.75rem; }

    .hero h1 {
        font-size: 2.25rem;
    }

    .nav-menu {
        position: fixed;
        top: var(--header-height);
        left: 0;
        right: 0;
        background-color: var(--bg-primary);
        flex-direction: column;
        padding: var(--spacing-lg);
        gap: var(--spacing-md);
        border-bottom: 1px solid var(--border-color);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all var(--transition-normal);
    }

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

    .menu-toggle {
        display: flex;
    }

    .grid-2,
    .grid-3,
    .grid-4 {
        grid-template-columns: 1fr;
    }

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

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

    .footer-links {
        flex-wrap: wrap;
        justify-content: center;
    }
}

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

    .section {
        padding: var(--spacing-2xl) 0;
    }

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

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

/* ============================================
   Print Styles
   ============================================ */
@media print {
    .header,
    .footer,
    .menu-toggle {
        display: none;
    }

    main {
        margin-top: 0;
    }

    .hero {
        background: none;
        color: var(--text-primary);
        padding: var(--spacing-lg) 0;
    }

    .hero h1 {
        color: var(--primary-color);
    }

    a {
        text-decoration: underline;
    }

    .card {
        box-shadow: none;
        border: 1px solid var(--border-color);
    }
}