* {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    background-color: #e9ecef;
    color: #252a2e;
    font-family: Arial, Helvetica, sans-serif;
    line-height: 1.6;
}

#navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 260px;
    height: 100vh;

    background-color: #343a40;
    color: #f1f3f5;

    border-right: 4px solid #868e96;
    overflow-y: auto;
}

#navbar header {
    padding: 24px 20px;
    background-color: #212529;
    color: #ffffff;

    font-family: "Courier New", monospace;
    font-size: 1.4rem;
    font-weight: bold;
    letter-spacing: 1px;

    border-bottom: 1px solid #495057;
}

.nav-link {
    display: block;
    padding: 14px 20px;

    color: #ced4da;
    text-decoration: none;

    border-bottom: 1px solid #495057;

    transition: background-color 0.15s, color 0.15s;
}

.nav-link:hover {
    background-color: #495057;
    color: #ffffff;
}

.nav-link:focus {
    outline: 2px solid #adb5bd;
    outline-offset: -2px;
}

#main-doc {
    margin-left: 260px;
    padding: 40px;
    max-width: 1100px;
}

.main-section {
    margin-bottom: 32px;
    padding: 28px;

    background-color: #f8f9fa;

    border: 1px solid #ced4da;
    border-left: 5px solid #495057;

    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.08);
}

.main-section header {
    margin: -28px -28px 20px -28px;
    padding: 16px 20px;

    background-color: #dee2e6;
    color: #212529;

    border-bottom: 1px solid #adb5bd;

    font-size: 1.5rem;
    font-weight: bold;
}

.main-section p {
    margin: 16px 0;
}

code {
    padding: 2px 5px;

    background-color: #e9ecef;
    color: #343a40;

    border: 1px solid #ced4da;
    border-radius: 2px;

    font-family: "Courier New", Courier, monospace;
}

pre {
    padding: 18px;

    background-color: #212529;
    color: #e9ecef;

    border: 1px solid #495057;
    border-left: 4px solid #868e96;

    overflow-x: auto;
}

pre code {
    padding: 0;

    background: none;
    color: inherit;

    border: none;

    font-family: "Courier New", Courier, monospace;
    font-size: 0.9rem;
    line-height: 1.5;
}

@media (max-width: 768px) {
    #navbar {
        position: relative;
        width: 100%;
        height: auto;

        border-right: none;
        border-bottom: 4px solid #868e96;
    }

    #navbar header {
        text-align: center;
    }

    #main-doc {
        margin-left: 0;
        padding: 20px;
    }

    .main-section {
        padding: 20px;
    }

    .main-section header {
        margin: -20px -20px 20px -20px;
    }
}