:root {
    --primary-color: #607D8B;
    --background-color: #f0f0f0;
    --card-background-color: #ffffff;
    --text-color: #333333;
    --headline-color: #222222;

    --font-family-sans-serif: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-family-monospace: "SF Mono", "Fira Code", "Fira Mono", "Roboto Mono", monospace;
}

body {
    background-color: var(--background-color);
    color: var(--text-color);
    font-family: var(--font-family-sans-serif);
    line-height: 1.6;
    margin: 0;
    padding: 0;
}

header {
    background-color: var(--card-background-color);
    border-bottom: 1px solid #eee;
    position: sticky;
    top: 0;
    z-index: 100;
}

nav ul {
    display: flex;
    justify-content: center;
    list-style: none;
    margin: 0;
    padding: 1rem;
}

nav a {
    color: var(--text-color);
    text-decoration: none;
    padding: 0.5rem 1rem;
    transition: color 0.3s ease;
}

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

main {
    padding: 2rem;
}

section {
    margin-bottom: 4rem;
}

h1, h2, h3 {
    color: var(--headline-color);
    text-align: center;
}

h1 {
    font-size: 3rem;
    margin-bottom: 0.5rem;
}

h2 {
    font-size: 2rem;
    margin-bottom: 2rem;
    color: var(--primary-color);
}

h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
}

.card {

    background-color: var(--card-background-color);

    border-radius: 5px;

    border: 1px solid #eee;

    padding: 2rem;

    margin-bottom: 2rem;

}

pre {
    background-color: #000;
    border-radius: 5px;
    color: #eee;
    font-family: var(--font-family-monospace);
    font-size: 0.9rem;
    overflow-x: auto;
    padding: 1.5rem;
    white-space: pre-wrap;
    word-wrap: break-word;
}


footer {
    text-align: center;
    padding: 1rem;
    margin-top: 4rem;
    color: #aaa;
}

@media (max-width: 768px) {
    header nav ul {
        flex-direction: column;
        align-items: center;
    }

    nav a {
        display: block;
        width: 100%;
        text-align: center;
    }
}