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

body {
    font-family: 'Noto Sans KR', -apple-system, BlinkMacSystemFont, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f5f5f5;
}

a {
    text-decoration: none;
    color: inherit;
}

/* Header & Navigation */
header {
    background: linear-gradient(135deg, #1a237e 0%, #3949ab 100%);
    color: white;
    padding: 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 10px rgba(0,0,0,0.2);
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
}

.logo img {
    height: 50px;
    width: auto;
}

.logo h1 {
    font-size: 1.5rem;
    font-weight: 700;
}

nav ul {
    display: flex;
    list-style: none;
    gap: 5px;
}

nav ul li a {
    display: block;
    padding: 12px 20px;
    border-radius: 8px;
    transition: all 0.3s ease;
    font-weight: 500;
}

nav ul li a:hover,
nav ul li a.active {
    background: rgba(255,255,255,0.2);
}

/* Mobile Menu */
.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    color: white;
    font-size: 1.5rem;
    cursor: pointer;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #1a237e 0%, #3949ab 50%, #5c6bc0 100%);
    color: white;
    padding: 60px 20px;
    text-align: center;
}

.hero-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    gap: 50px;
}

.hero-text {
    flex: 1;
    text-align: left;
}

.hero-text h2 {
    font-size: 2.5rem;
    margin-bottom: 20px;
    line-height: 1.3;
}

.hero-text p {
    font-size: 1.1rem;
    opacity: 0.9;
    margin-bottom: 30px;
}

.hero-image {
    flex: 1;
}

.hero-image img {
    max-width: 100%;
    border-radius: 15px;
    box-shadow: 0 20px 40px rgba(0,0,0,0.3);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 14px 30px;
    border-radius: 8px;
    font-weight: 600;
    font-size: 1rem;
    transition: all 0.3s ease;
    cursor: pointer;
    border: none;
}

.btn-primary {
    background: #ff9800;
    color: white;
}

.btn-primary:hover {
    background: #f57c00;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(255,152,0,0.4);
}

.btn-secondary {
    background: white;
    color: #1a237e;
}

.btn-secondary:hover {
    background: #e8eaf6;
    transform: translateY(-2px);
}

.btn-download {
    background: linear-gradient(135deg, #4caf50, #2e7d32);
    color: white;
    padding: 15px 35px;
    font-size: 1.1rem;
}

.btn-download:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 20px rgba(76,175,80,0.4);
}

/* Main Content */
main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 40px 20px;
}

/* Section Styles */
.section {
    margin-bottom: 50px;
}

.section-title {
    font-size: 1.8rem;
    color: #1a237e;
    margin-bottom: 30px;
    padding-bottom: 15px;
    border-bottom: 3px solid #3949ab;
    display: flex;
    align-items: center;
    gap: 10px;
}

.section-title i {
    color: #ff9800;
}

/* Page Header */
.page-header {
    background: linear-gradient(135deg, #1a237e 0%, #3949ab 100%);
    color: white;
    padding: 40px 20px;
    text-align: center;
    margin-bottom: 40px;
}

.page-header h2 {
    font-size: 2rem;
    margin-bottom: 10px;
}

.page-header p {
    opacity: 0.9;
}

/* Card Grid */
.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 25px;
}

/* Card Styles */
.card {
    background: white;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    transition: all 0.3s ease;
}

.card:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 30px rgba(0,0,0,0.15);
}

.card-image {
    width: 100%;
    height: 180px;
    object-fit: cover;
    background: #e8eaf6;
}

.card-content {
    padding: 20px;
}

.card-title {
    font-size: 1.1rem;
    font-weight: 600;
    color: #1a237e;
    margin-bottom: 10px;
    line-height: 1.4;
}

.card-description {
    font-size: 0.9rem;
    color: #666;
    margin-bottom: 15px;
}

.card-link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: #3949ab;
    font-weight: 500;
    transition: color 0.3s ease;
}

.card-link:hover {
    color: #ff9800;
}

/* Download Cards */
.download-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 25px;
}

.download-card {
    background: white;
    border-radius: 12px;
    padding: 30px;
    text-align: center;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    transition: all 0.3s ease;
    border: 2px solid transparent;
}

.download-card:hover {
    border-color: #3949ab;
    transform: translateY(-5px);
}

.download-card.featured {
    border-color: #ff9800;
    background: linear-gradient(to bottom, #fff9e6, white);
}

.download-card .version {
    display: inline-block;
    background: #e8eaf6;
    color: #1a237e;
    padding: 5px 15px;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 15px;
}

.download-card.featured .version {
    background: #ff9800;
    color: white;
}

.download-card h3 {
    font-size: 1.3rem;
    color: #1a237e;
    margin-bottom: 10px;
}

.download-card p {
    color: #666;
    margin-bottom: 20px;
}

.download-card .btn {
    width: 100%;
}

/* Video Card */
.video-card {
    background: white;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    transition: all 0.3s ease;
}

.video-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 30px rgba(0,0,0,0.15);
}

.video-thumbnail {
    position: relative;
    width: 100%;
    padding-top: 56.25%; /* 16:9 ratio */
    background: #000;
}

.video-thumbnail img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.video-thumbnail .play-btn {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 60px;
    height: 60px;
    background: rgba(255,0,0,0.9);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
}

.video-thumbnail .play-btn::after {
    content: '';
    width: 0;
    height: 0;
    border-left: 20px solid white;
    border-top: 12px solid transparent;
    border-bottom: 12px solid transparent;
    margin-left: 5px;
}

.video-card:hover .play-btn {
    transform: translate(-50%, -50%) scale(1.1);
    background: rgba(255,0,0,1);
}

.video-card .card-content {
    padding: 15px 20px;
}

.video-card .card-title {
    font-size: 1rem;
    margin-bottom: 5px;
}

.video-card .video-number {
    font-size: 0.85rem;
    color: #999;
}

/* Quick Links */
.quick-links {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-top: 40px;
}

.quick-link-card {
    background: white;
    border-radius: 12px;
    padding: 30px;
    text-align: center;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    transition: all 0.3s ease;
}

.quick-link-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(0,0,0,0.15);
}

.quick-link-card i {
    font-size: 3rem;
    color: #3949ab;
    margin-bottom: 15px;
}

.quick-link-card h3 {
    font-size: 1.2rem;
    color: #1a237e;
    margin-bottom: 10px;
}

.quick-link-card p {
    color: #666;
    font-size: 0.9rem;
}

/* Footer */
footer {
    background: #1a237e;
    color: white;
    padding: 40px 20px;
    margin-top: 60px;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    text-align: center;
}

.footer-content p {
    opacity: 0.8;
    margin-bottom: 10px;
}

.footer-content a {
    color: #ff9800;
}

/* Responsive Design */
@media (max-width: 768px) {
    .header-content {
        flex-wrap: wrap;
    }
    
    .mobile-menu-btn {
        display: block;
    }
    
    nav {
        display: none;
        width: 100%;
        margin-top: 15px;
    }
    
    nav.active {
        display: block;
    }
    
    nav ul {
        flex-direction: column;
    }
    
    nav ul li a {
        padding: 12px 15px;
        border-radius: 5px;
    }
    
    .hero-content {
        flex-direction: column;
        text-align: center;
    }
    
    .hero-text {
        text-align: center;
    }
    
    .hero-text h2 {
        font-size: 1.8rem;
    }
    
    .card-grid {
        grid-template-columns: 1fr;
    }
    
    .download-grid {
        grid-template-columns: 1fr;
    }
}

/* Utility Classes */
.text-center {
    text-align: center;
}

.mt-20 {
    margin-top: 20px;
}

.mb-20 {
    margin-bottom: 20px;
}