:root {
    --primary-color: #00adb5;
    --secondary-color: #393e46;
    --dark-bg: #222831;
    --light-text: #eeeeee;
    --gray-text: #b0b0b0;
    --header-bg: rgba(34, 40, 49, 0.95);
}

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

body {
    font-family: 'Noto Sans KR', sans-serif;
    background-color: var(--dark-bg);
    color: var(--light-text);
    line-height: 1.6;
}

.container {
    width: 90%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header */
header {
    background-color: var(--header-bg);
    padding: 20px 0;
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 10px rgba(0,0,0,0.3);
}

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

.logo h1 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.sub-logo {
    font-size: 0.8rem;
    color: var(--gray-text);
    letter-spacing: 1px;
}

nav ul {
    list-style: none;
    display: flex;
}

nav ul li {
    margin-left: 30px;
}

nav ul li a {
    text-decoration: none;
    color: var(--light-text);
    font-weight: 500;
    transition: color 0.3s;
}

nav ul li a:hover {
    color: var(--primary-color);
}

/* Hero Section */
#hero {
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    background: linear-gradient(rgba(0,0,0,0.7), rgba(0,0,0,0.7)), url('https://source.unsplash.com/random/1920x1080/?engineering,technology') no-repeat center center/cover;
    padding-top: 80px; /* Header height */
}

.hero-content h2 {
    font-size: 3rem;
    margin-bottom: 20px;
    line-height: 1.3;
}

.hero-content p {
    font-size: 1.2rem;
    margin-bottom: 40px;
    color: var(--gray-text);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 12px 30px;
    background-color: var(--primary-color);
    color: #fff;
    text-decoration: none;
    border-radius: 5px;
    font-weight: 700;
    transition: background 0.3s;
}

.btn:hover {
    background-color: #007f85;
}

.btn-outline {
    display: inline-block;
    padding: 10px 25px;
    border: 2px solid var(--primary-color);
    color: var(--primary-color);
    text-decoration: none;
    border-radius: 5px;
    font-weight: 700;
    transition: all 0.3s;
}

.btn-outline:hover {
    background-color: var(--primary-color);
    color: #fff;
}

/* Sections */
.section {
    padding: 80px 0;
}

.section-title {
    font-size: 2rem;
    text-align: center;
    margin-bottom: 20px;
    color: var(--primary-color);
}

.section-desc {
    text-align: center;
    max-width: 700px;
    margin: 0 auto 50px;
    color: var(--gray-text);
}

.dark-bg {
    background-color: #2b323c;
}

/* Patent Card */
.patent-card {
    background-color: var(--secondary-color);
    padding: 40px;
    border-radius: 10px;
    text-align: center;
    box-shadow: 0 4px 15px rgba(0,0,0,0.2);
    max-width: 600px;
    margin: 0 auto;
}

.patent-card h4 {
    font-size: 1.5rem;
    margin-bottom: 15px;
}

.patent-card p {
    margin-bottom: 30px;
    color: var(--gray-text);
}

/* Contact Info */
.contact-info {
    text-align: center;
    font-size: 1.1rem;
}

.contact-info p {
    margin: 10px 0;
}

/* Footer */
footer {
    background-color: #1a1d24;
    padding: 30px 0;
    text-align: center;
    color: var(--gray-text);
    font-size: 0.9rem;
}

/* Responsive */
@media (max-width: 768px) {
    .hero-content h2 {
        font-size: 2rem;
    }
    
    header .container {
        flex-direction: column;
    }
    
    nav ul {
        margin-top: 20px;
    }
    
    nav ul li {
        margin: 0 10px;
    }
}