html {
    font-size: 10px;
}

* {
    margin: 0;
}

body {
    font-family: 'Open Sans', Arial, sans-serif;
    font-size: 1.6rem;
}

#navbar {
    position: fixed;
    min-width: 250px;
    top: 0px;
    left: 0px;
    width: 250px;
    height: 100%;
    padding: 2rem;
    background-color: #f5f5f5;
    border-right: 2px solid;
    border-color: #ccc;
}

#navbar>header {
    font-size: 2.8rem;
    font-weight: bold;
    margin-bottom: 2rem;
}

#navbar>ul {
    list-style: none;
    height: 88%;
    padding: 0 0 0 2rem;
    overflow-y: auto;
    overflow-x: hidden;
}

#navbar>ul>li {
    margin-bottom: 2rem;
}

#navbar>ul>li>a {
    color: #222;
    text-decoration: none;
}

#main-doc {
    position: absolute;
    margin-left: 30rem;
    padding: 2rem;
}

section header {
    font-size: 2.8rem;
    font-weight: normal;
    margin: 4rem 0 1rem 0;
}

#Introduction {
    margin-top: -2rem;
}

section article {
    line-height: 1.5;
}

p {
    margin-top: 1rem;
}

section article ul li {
    margin: 1rem 0;
}

code {
    display: block;
    background-color: #f5f5f5;
    color: #1f1f1f;
    font-size: 1.4rem;
    margin: 2rem;
    padding: 2rem;
}

@media screen and (max-width: 640px) {
    #navbar ul {
        border: 1px solid;
        height: 207px;
    }
    #navbar ul li {
        margin-top: 1rem;
    }
    #navbar {
        background-color: #fdfdfd;
        position: absolute;
        top: 0;
        padding: 0;
        margin: 0;
        width: 100%;
        max-height: 275px;
        border: none;
        z-index: 1;
        border-bottom: 2px solid #ccc;
    }
    #navbar header {
        margin-top: 1rem;
        text-align: center;
    }
    #main-doc {
        position: relative;
        margin-left: 0;
        margin-top: 270px;
    }
}