* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Pretendard', sans-serif;
}

body {
    width: 100%;
    height: 100vh;
    background-image: url('images/nuclear_bg.jpg');
    background-size: cover;
    background-position: center;
    color: white;
}

body::before {
    content: "";
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: -1;
}

header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 70px;
    z-index: 10;
    display: flex;
    align-items: center;
}

.header-container {
    width: 100%;
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 20px;
}

.logo {
    display: flex;
    align-items: center;
    text-decoration: none;
    color: #f4f4f4;
    font-weight: 800;
    font-size: 2rem;
    gap: 10px;
}

.logo img {
    width: 40px;
}

main {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;     
    padding: 120px 20px 60px 20px;
    z-index: 10;
}

.main-title {
    font-size: 7rem;
    font-weight: 800;
    letter-spacing: 5px;
    margin-bottom: 10px;
    text-shadow: 2px 2px 10px rgba(0,0,0,0.5);
}

.sub-title {
    font-size: 1.5rem;
    font-weight: 300;
    color: #e0e0e0;
}

.description {
    font-size: 1.5rem;
    line-height: 1.6;
    font-weight: 600;
    text-shadow: 1px 1px 5px rgba(0,0,0,0.5);
}

@media (max-width: 768px) {
    .main-title { font-size: 3rem; }
    .sub-title { font-size: 1rem; }
    .description { font-size: 1rem; }
}

.home-btn {
    margin-top: 60px;
    padding: 15px 60px;
    border: 2px solid #5c7cfa; 
    color: white;
    text-decoration: none;
    font-size: 1.5rem;
    font-weight: 600;
    border-radius: 50px;
    transition: all 0.3s ease;
    backdrop-filter: blur(5px);
}

.home-btn:hover {
    background-color: #1f283e; 
    border-color: #1f283e;
    color: white;
    transform: translateY(-3px);
    box-shadow: 0 0 20px rgba(31, 40, 62, 0.8); 
}

.card-container {
    display: flex;
    justify-content: center;
    gap: 40px; 
    margin-top: 80px; 
    width: 100%;
    max-width: 1400px;
    flex-wrap: wrap;
}

.info-card {
    background-color: white;
    width: 400px;  
    height: 400px; 
    border-radius: 30px; 
    overflow: hidden;
    display: flex;
    flex-direction: column;
    box-shadow: 0 10px 20px rgba(0,0,0,0.3);
    border: 1px solid rgba(0, 0, 0, 0.1);
}

.card-top {
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #333;
    font-weight: 700;
    font-size: 1.2rem;
    background: white;
}

.card-img-area {
    flex-grow: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: #e0e0e0; 
    overflow: hidden;
    padding: 1px;
}

.card-img-area img {
    width: 100%;
    height: 100%;
    object-fit: cover; 
    object-position: top center; 
}

.card-bottom {
    height: 40px;
    background: white;
}