:root {
    --primary-color: #0d1b2a;
    /* Deep Navy */
    --secondary-color: #1b263b;
    /* Lighter Navy */
    --accent-color: #00b4d8;
    /* Neon Teal/Blue */
    --text-color: #e0e1dd;
    /* Off-white */
    --text-muted: #778da9;
    --background: #02040a;
    /* Almost Black */
    --card-bg: #0f1623;
    --font-main: 'Noto Sans KR', sans-serif;
    --transition: all 0.3s ease;
}

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

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

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

ul {
    list-style: none;
}

/* Navigation */
.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 5%;
    background-color: rgba(13, 27, 42, 0.95);
    backdrop-filter: blur(10px);
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
    border-bottom: 1px solid rgba(0, 180, 216, 0.1);
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent-color);
    letter-spacing: -0.5px;
}

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

.nav-links a {
    font-weight: 500;
    font-size: 1rem;
    position: relative;
    padding-bottom: 5px;
}

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

.nav-links a:hover {
    color: var(--accent-color);
}

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

.hamburger {
    display: none;
    cursor: pointer;
    font-size: 1.5rem;
}

/* Hero Section */
.hero {
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    background: linear-gradient(rgba(2, 4, 10, 0.7), rgba(2, 4, 10, 0.8)), url('lab_hero_background.png');
    background-size: cover;
    background-position: center;
    padding: 0 1rem;
    margin-top: 0;
    /* Cover behind nav */
}

.hero-content {
    max-width: 900px;
    animation: fadeInUp 1s ease-out;
}

.hero h1 {
    font-size: 3.5rem;
    margin-bottom: 1rem;
    text-transform: uppercase;
    letter-spacing: 2px;
}

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

.hero p {
    font-size: 1.25rem;
    color: var(--text-muted);
    margin-bottom: 2.5rem;
}

.btn {
    display: inline-block;
    padding: 0.8rem 2rem;
    border: 1px solid var(--accent-color);
    color: var(--accent-color);
    border-radius: 5px;
    font-weight: 600;
    transition: var(--transition);
}

.btn:hover {
    background-color: var(--accent-color);
    color: var(--background);
    box-shadow: 0 0 15px rgba(0, 180, 216, 0.4);
}

/* Sections */
section {
    padding: 5rem 5%;
}

.section-title {
    font-size: 2.5rem;
    margin-bottom: 3rem;
    text-align: center;
    position: relative;
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 3px;
    background: var(--accent-color);
    margin: 1rem auto 0;
}

/* About / Cards */
.grid-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.card {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 10px;
    border: 1px solid rgba(255, 255, 255, 0.05);
    transition: var(--transition);
}

.card:hover {
    transform: translateY(-5px);
    border-color: var(--accent-color);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
}

.card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--accent-color);
}

.card ul {
    list-style: disc;
    padding-left: 1.5rem;
    color: var(--text-muted);
}

.card li {
    margin-bottom: 0.5rem;
}

/* Contact/Footer */
footer {
    background: var(--primary-color);
    padding: 3rem 5%;
    text-align: center;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
}

footer p {
    color: var(--text-muted);
    margin-bottom: 0.5rem;
}

/* Responsive */
@media (max-width: 768px) {
    .nav-links {
        display: none;
        flex-direction: column;
        position: absolute;
        top: 70px;
        right: 0;
        background: var(--primary-color);
        width: 100%;
        padding: 2rem;
        text-align: center;
    }

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

    .hamburger {
        display: block;
    }

    .hero h1 {
        font-size: 2.5rem;
    }
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Members Page */
.professor-profile {
    display: flex;
    gap: 3rem;
    align-items: center;
    background: var(--card-bg);
    padding: 3rem;
    border-radius: 15px;
    border: 1px solid rgba(0, 180, 216, 0.2);
    margin-bottom: 4rem;
    flex-wrap: wrap;
}

.prof-img-placeholder {
    width: 200px;
    height: 250px;
    background: linear-gradient(135deg, var(--secondary-color), var(--primary-color));
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 3rem;
    color: var(--accent-color);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
}

.prof-info h2 {
    font-size: 2rem;
    color: var(--accent-color);
    margin-bottom: 0.5rem;
}

.prof-info h4 {
    color: var(--text-muted);
    font-weight: 400;
    margin-bottom: 1.5rem;
    font-size: 1.1rem;
}

.member-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 2rem;
}

.member-card {
    background: var(--card-bg);
    padding: 2rem 1rem;
    border-radius: 10px;
    text-align: center;
    border: 1px solid rgba(255, 255, 255, 0.05);
    transition: var(--transition);
}

.member-card:hover {
    transform: translateY(-5px);
    border-color: var(--accent-color);
}

.member-avatar {
    width: 100px;
    height: 100px;
    background: #2b2d42;
    border-radius: 50%;
    margin: 0 auto 1rem;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
}

/* Contact Page */
.contact-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
}

.contact-info,
.join-us {
    background: var(--card-bg);
    padding: 2.5rem;
    border-radius: 10px;
}

.contact-item {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.contact-item i {
    color: var(--accent-color);
    font-size: 1.2rem;
    margin-top: 5px;
}

.highlight-box {
    background: rgba(0, 180, 216, 0.05);
    /* Very light accent */
    border-left: 4px solid var(--accent-color);
    padding: 1.5rem;
    margin-top: 1rem;
    border-radius: 0 5px 5px 0;
}

@media (max-width: 768px) {
    .professor-profile {
        flex-direction: column;
        text-align: center;
    }

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