:root {
    --primary-color: #3498db;
    --secondary-color: #2c3e50;
    --accent-color: #e74c3c;
    --light-color: #ecf0f1;
    --dark-color: #34495e;
}

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

body {
    font-family: 'Noto Sans KR', sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: var(--light-color);
}

header {
    background-color: var(--primary-color);
    color: white;
    text-align: center;
    padding: 2rem 0;
}

header h1 {
    margin-bottom: 0.5rem;
}

nav {
    background-color: var(--secondary-color);
    padding: 1rem 0;
}

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

nav ul li {
    margin: 0 1rem;
}

nav ul li a {
    color: white;
    text-decoration: none;
    font-weight: bold;
    transition: color 0.3s;
}

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

main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

section {
    margin-bottom: 3rem;
}

section h2 {
    color: var(--secondary-color);
    margin-bottom: 1.5rem;
    border-bottom: 2px solid var(--primary-color);
    padding-bottom: 0.5rem;
}

#bridge-model-container {
    width: 100%;
    height: 500px;
    background-color: #f5f5f5;
    border-radius: 8px;
    margin-bottom: 1rem;
    position: relative;
}

.model-controls {
    display: flex;
    justify-content: center;
    margin-bottom: 1rem;
}

.model-controls button {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 0.5rem 1rem;
    margin: 0 0.5rem;
    border-radius: 4px;
    cursor: pointer;
    transition: background-color 0.3s;
}

.model-controls button:hover {
    background-color: var(--dark-color);
}

.model-instructions {
    text-align: center;
    color: #777;
    margin-bottom: 1rem;
}

.improvement-item {
    background-color: white;
    border-radius: 8px;
    padding: 1.5rem;
    margin-bottom: 1rem;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

.improvement-item h3 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.height-specification {
    display: inline-block;
    background-color: var(--primary-color);
    color: white;
    padding: 0.1rem 0.5rem;
    border-radius: 4px;
    margin-left: 0.5rem;
    font-size: 0.9em;
}

.resource-links, .school-resources {
    background-color: white;
    border-radius: 8px;
    padding: 1.5rem;
    margin-bottom: 1rem;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

.resource-links h3, .school-resources h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.resource-links ul {
    margin-left: 2rem;
}

.resource-links a {
    color: var(--accent-color);
    font-weight: bold;
}

footer {
    background-color: var(--secondary-color);
    color: white;
    text-align: center;
    padding: 2rem 0;
    margin-top: 2rem;
}

@media (max-width: 768px) {
    nav ul {
        flex-direction: column;
        align-items: center;
    }
    
    nav ul li {
        margin: 0.5rem 0;
    }
    
    #bridge-model-container {
        height: 300px;
    }
    
    .model-controls {
        flex-direction: column;
    }
    
    .model-controls button {
        margin: 0.5rem 0;
    }
}

/* 고효율 난간 페이지 스타일 */
.design-features {
    margin-bottom: 2rem;
}

.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
    margin-top: 1rem;
}

.feature-item {
    background-color: white;
    border-radius: 8px;
    padding: 1.5rem;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

.feature-item h4 {
    color: var(--primary-color);
    margin-bottom: 0.8rem;
}

.specs-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.spec-item {
    background-color: white;
    border-radius: 8px;
    padding: 1.2rem;
    text-align: center;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

.spec-item h4 {
    color: var(--secondary-color);
    margin-bottom: 0.5rem;
}

.material-options {
    background-color: white;
    border-radius: 8px;
    padding: 1.5rem;
    margin-bottom: 2rem;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

.effectiveness-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin: 1.5rem 0;
}

.stat-item {
    background-color: var(--primary-color);
    color: white;
    border-radius: 8px;
    padding: 1.5rem;
    text-align: center;
}

.stat-item h3 {
    color: white;
    font-size: 1.8rem;
    margin-bottom: 0.5rem;
}

#railing-model-container {
    width: 100%;
    height: 500px;
    background-color: #f5f5f5;
    border-radius: 8px;
    margin-bottom: 1rem;
    position: relative;
}

@media (max-width: 768px) {
    .feature-grid,
    .specs-container,
    .effectiveness-stats {
        grid-template-columns: 1fr;
    }
    
    #railing-model-container {
        height: 300px;
    }
}