body {
    font-family: 'Arial', sans-serif;
    margin: 0;
    padding: 0;
    background: linear-gradient(to bottom, #87CEEB, #E0FFFF);
    color: #333;
    line-height: 1.6;
}

header {
    background: #1E90FF;
    color: white;
    text-align: center;
    padding: 2rem;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

header h1 {
    font-size: 3rem;
    margin: 0;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
}

header p {
    font-size: 1.5rem;
    margin: 0.5rem 0;
}

nav ul {
    list-style: none;
    padding: 0;
    display: flex;
    justify-content: center;
    gap: 1.5rem;
}

nav a {
    color: white;
    text-decoration: none;
    font-weight: bold;
    padding: 0.5rem 1rem;
    background: #FF4500;
    border-radius: 5px;
    transition: background 0.3s;
}

nav a:hover {
    background: #FFD700;
    color: #333;
}

main {
    max-width: 800px;
    margin: 2rem auto;
    padding: 0 1rem;
}

section {
    background: white;
    padding: 2rem;
    margin: 1rem 0;
    border-radius: 10px;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
    border-left: 5px solid #FF4500;
}

h2 {
    color: #1E90FF;
    font-size: 2rem;
    margin-bottom: 1rem;
}

h3 {
    color: #FF4500;
    font-size: 1.5rem;
}

.principle, .system {
    margin-bottom: 1.5rem;
}

ul {
    list-style: square;
    padding-left: 1.5rem;
}

ul li {
    margin: 0.5rem 0;
    font-size: 1.1rem;
}

.chart {
    background: #f0f0f0;
    padding: 1rem;
    border: 2px solid #1E90FF;
    border-radius: 5px;
    font-family: 'Courier New', monospace;
    font-size: 0.9rem;
    text-align: left;
    overflow-x: auto;
}

footer {
    text-align: center;
    padding: 1rem;
    background: #1E90FF;
    color: white;
    width: 100%;
}

@media (max-width: 600px) {
    header h1 {
        font-size: 2rem;
    }
    nav ul {
        flex-direction: column;
        gap: 0.5rem;
    }
    section {
        padding: 1rem;
    }
}