:root {
    /* Color Palette */
    --color-primary: #0a4d68; /* Deep Aquatic Blue */
    --color-primary-light: #088395;
    --color-secondary: #05bfdb;
    --color-accent: #00ffca; /* Eco Green Accent */
    
    --color-bg: #f8fcfd;
    --color-bg-alt: #eef8fa;
    --color-surface: #ffffff;
    
    --color-text-main: #1e293b;
    --color-text-muted: #64748b;
    --color-white: #ffffff;
    
    /* Typography */
    --font-heading: 'Outfit', sans-serif;
    --font-body: 'Noto Sans KR', sans-serif;
    
    /* Spacing & Layout */
    --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
    --color-border: #e0e6ed;
    
    --glass-bg: rgba(255, 255, 255, 0.95);
    --glass-border: rgba(255, 255, 255, 0.2);
    --glass-shadow: 0 8px 32px rgba(0, 0, 0, 0.05);
    --border-radius: 16px;
    --shadow-soft: 0 10px 30px rgba(10, 77, 104, 0.08);
}

/* Dark Mode Preferences */
@media (prefers-color-scheme: dark) {
    :root {
        --color-bg: #03151f;
        --color-bg-alt: #051f2e;
        --color-surface: #0a2b3d;
        --color-text-main: #f1f5f9;
        --color-text-muted: #94a3b8;
        --glass-bg: rgba(10, 43, 61, 0.95);
        --glass-border: rgba(255, 255, 255, 0.1);
        --shadow-soft: 0 10px 30px rgba(0, 0, 0, 0.3);
    }
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-body);
    color: var(--color-text-main);
    background-color: var(--color-bg);
    line-height: 1.6;
    overflow-x: hidden;
}

h1, h2, h3, h4, .logo, .sub-heading {
    font-family: var(--font-heading);
}

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

ul {
    list-style: none;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

.section-padding {
    padding: 100px 0;
}

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

.mt-2 {
    margin-top: 16px;
}

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

/* Typography elements */
.sub-heading {
    display: block;
    color: var(--color-secondary);
    font-weight: 700;
    font-size: 1.1rem;
    letter-spacing: 2px;
    text-transform: uppercase;
    margin-bottom: 12px;
}

h2 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 40px;
    color: var(--color-primary);
}

@media (prefers-color-scheme: dark) {
    h2 {
        color: var(--color-secondary);
    }
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 14px 32px;
    border-radius: 30px;
    font-weight: 700;
    cursor: pointer;
    text-align: center;
}

.primary-btn {
    background: linear-gradient(135deg, var(--color-secondary), var(--color-primary-light));
    color: var(--color-white);
    box-shadow: 0 8px 20px rgba(5, 191, 219, 0.3);
}

.primary-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 12px 25px rgba(5, 191, 219, 0.4);
}

.outline-btn {
    border: 2px solid rgba(255, 255, 255, 0.5);
    color: var(--color-white);
    background: transparent;
}

.outline-btn:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: var(--color-white);
    transform: translateY(-3px);
}

/* Navbar */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    padding: 12px 0;
    transition: var(--transition);
    background: var(--glass-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--glass-border);
    box-shadow: 0 4px 20px rgba(0,0,0,0.05);
}

.navbar.scrolled {
    padding: 12px 0;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 900;
    color: var(--color-primary);
    text-shadow: 0 2px 4px rgba(0,0,0,0.1);
    display: flex;
    align-items: center;
}

#logo-img {
    max-height: 45px;
    width: auto;
}

.navbar.scrolled .logo,
.navbar:not(.scrolled) .logo {
    color: var(--color-primary); 
}
@media (prefers-color-scheme: dark) {
    .navbar.scrolled .logo, .navbar:not(.scrolled) .logo { color: var(--color-white); }
}

.nav-links {
    display: flex;
    gap: 32px;
}

.nav-links li a {
    color: var(--color-primary);
    font-weight: 500;
    font-size: 1.05rem;
    position: relative;
}

.nav-links li a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0%;
    height: 2px;
    background: var(--color-accent);
    transition: var(--transition);
}

.nav-links li a:hover::after {
    width: 100%;
}

.hamburger {
    display: none;
    flex-direction: column;
    gap: 6px;
    cursor: pointer;
}

.hamburger span {
    width: 30px;
    height: 3px;
    background: var(--color-white);
    transition: var(--transition);
}

/* Hero Section */
.hero {
    height: 100vh;
    min-height: 600px;
    background: url('../assets/hero_bg.jpg') no-repeat center center/cover;
    position: relative;
    display: flex;
    align-items: center;
    background-color: var(--color-primary); /* Fallback */
}

.hero-overlay {
    position: absolute;
    top: 0; left: 0; width: 100%; height: 100%;
    background: linear-gradient(135deg, rgba(10, 77, 104, 0.8) 0%, rgba(5, 191, 219, 0.2) 100%);
}

.hero-content {
    position: relative;
    z-index: 10;
    width: 100%;
}

.hero-glass-card {
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(24px);
    -webkit-backdrop-filter: blur(24px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    padding: 64px;
    border-radius: 32px;
    max-width: 650px;
    box-shadow: 0 30px 60px rgba(0,0,0,0.3);
    color: var(--color-white);
}

.hero-badge {
    display: inline-block;
    padding: 6px 16px;
    background: rgba(0, 255, 202, 0.2);
    border: 1px solid var(--color-accent);
    color: var(--color-accent);
    border-radius: 30px;
    font-size: 0.9rem;
    font-weight: 700;
    margin-bottom: 24px;
    letter-spacing: 1px;
}

.hero h1 {
    font-size: 3.5rem;
    line-height: 1.2;
    margin-bottom: 24px;
    font-weight: 900;
    background: linear-gradient(to right, #ffffff, #c2f0fc);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    text-shadow: 0 10px 30px rgba(0,0,0,0.1);
}

.hero p {
    font-size: 1.2rem;
    margin-bottom: 40px;
    color: rgba(255, 255, 255, 0.9);
    line-height: 1.6;
}

.hero-actions {
    display: flex;
    gap: 16px;
}

/* About Section */
.about-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 64px;
    align-items: center;
}

.about-text p {
    margin-bottom: 16px;
    font-size: 1.1rem;
    color: var(--color-text-muted);
}

.about-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    gap: 24px;
}

.stat-card {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    backdrop-filter: blur(10px);
    padding: 32px 24px;
    border-radius: var(--border-radius);
    text-align: center;
    box-shadow: var(--shadow-soft);
    transition: var(--transition);
}

.stat-card:hover {
    transform: translateY(-10px);
    border-color: var(--color-secondary);
}

.stat-num {
    display: block;
    font-size: 2.5rem;
    font-weight: 900;
    color: var(--color-primary-light);
    margin-bottom: 8px;
    font-family: var(--font-heading);
}

.stat-label {
    font-weight: 500;
    color: var(--color-text-main);
}

/* Background alt */
.bg-alt {
    background-color: var(--color-bg-alt);
}

/* Research Section */
.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 32px;
}

.research-card {
    background: var(--color-surface);
    padding: 40px 32px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-soft);
    transition: var(--transition);
    border: 1px solid transparent;
}

.research-card:hover {
    transform: translateY(-10px);
    border-color: var(--color-accent);
    box-shadow: 0 20px 40px rgba(0, 255, 202, 0.1);
}

.research-icon {
    font-size: 3rem;
    margin-bottom: 24px;
    display: inline-block;
    padding: 16px;
    background: var(--color-bg-alt);
    border-radius: 50%;
}

.research-card h3 {
    font-size: 1.25rem;
    margin-bottom: 16px;
    color: var(--color-text-main);
}

.research-card p {
    color: var(--color-text-muted);
}

/* Resources Section */
.resource-list {
    max-width: 800px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.resource-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--color-surface);
    padding: 24px 32px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-soft);
    transition: var(--transition);
    cursor: pointer;
    border-left: 4px solid transparent;
}

.resource-item:hover {
    transform: translateX(10px);
    border-left-color: var(--color-secondary);
}

.resource-title {
    font-weight: 700;
    font-size: 1.1rem;
    color: var(--color-text-main);
}

.resource-meta {
    display: flex;
    gap: 16px;
    align-items: center;
}

.resource-type {
    background: var(--color-bg-alt);
    color: var(--color-primary-light);
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 700;
}

.resource-date {
    color: var(--color-text-muted);
    font-size: 0.9rem;
}

/* Contact Section */
.contact-wrapper {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 48px;
    background: var(--color-surface);
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: var(--shadow-soft);
}

.contact-info {
    padding: 64px 48px;
}

.contact-info h3 {
    font-size: 1.8rem;
    margin-bottom: 32px;
    color: var(--color-primary);
}

@media (prefers-color-scheme: dark) {
    .contact-info h3 { color: var(--color-secondary); }
}

.contact-details {
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.contact-details li {
    display: flex;
    align-items: flex-start;
    gap: 16px;
    font-size: 1.1rem;
}

.contact-details i {
    font-style: normal;
    font-size: 1.5rem;
}

.contact-map {
    width: 100%;
    height: 100%;
    min-height: 400px;
}

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

/* Footer */
.footer {
    background: #f8f9fa;
    color: var(--color-text-main);
    padding: 40px 0;
}

.footer-logo {
    color: var(--color-primary);
    margin-bottom: 16px;
}

/* Animations */
.fade-up {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.8s ease-out, transform 0.8s ease-out;
}

.fade-up.visible {
    opacity: 1;
    transform: translateY(0);
}

.delay-1 { transition-delay: 0.1s; }
.delay-2 { transition-delay: 0.2s; }
.delay-3 { transition-delay: 0.3s; }

/* Responsive */
@media (max-width: 992px) {
    .hero h1 { font-size: 2.8rem; }
    .hero-glass-card { padding: 48px; max-width: 90%; }
    .about-content, .contact-wrapper {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .navbar { padding: 16px 0; background: var(--glass-bg); backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px); }
    .nav-links {
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background: var(--color-surface);
        flex-direction: column;
        gap: 0;
        clip-path: circle(0% at 100% 0);
        transition: clip-path 0.5s ease-out;
    }
    
    .nav-links.active {
        clip-path: circle(150% at 100% 0);
    }
    
    .nav-links li {
        width: 100%;
        text-align: center;
    }
    
    .nav-links li a {
        display: block;
        padding: 20px;
        color: var(--color-text-main);
        border-bottom: 1px solid var(--color-bg-alt);
    }
    
    .hamburger { display: flex; }
    .navbar:not(.scrolled) .logo { color: var(--color-primary); }
    @media (prefers-color-scheme: dark) { .navbar:not(.scrolled) .logo { color: var(--color-white); } }
    
    .hero-glass-card { padding: 32px 24px; border-radius: 20px; }
    .hero h1 { font-size: 2.2rem; }
    .hero p { font-size: 1.05rem; margin-bottom: 24px; }
    .hero-actions { flex-direction: column; width: 100%; }
    .hero-actions .btn { width: 100%; text-align: center; }

    .resource-item { flex-direction: column; align-items: flex-start; gap: 12px; }
}

@media (max-width: 480px) {
    .hero h1 { font-size: 1.8rem; }
}