@media (min-width:961px) {
    .div-main-section {
        max-width: 961px;
        position: relative;
        left: 290px;
    }

    #navbar {
        position: fixed;
    }

}

nav {
    border: 1px solid gray;
    border-right: 2px solid gray;
    height: 100%;
    min-width: 290px;
    width: 290px;
}

.div-navbar header,
.div-navbar p {
    border-bottom: 1px solid gray;
    margin: 0 0;
    padding: 10px 10px;
    text-align: left;
}

.div-navbar header {
    text-align: center;
    font-size: 2em;
}



.div-main-section {
    margin-left: 10px;
    min-width: 500px;
    padding: 20px 20px;
}

.main-section>header {
    font-size: 2em;
}

.main-section>p {
    margin: 10px 10px;
}

.main-section>pre {
    margin: 10px 20px;
    background-color: lightgray;
    overflow: auto;
}

#main-doc {
    display: flex;
}