styles.css

/*body{
    margin-left: 250px;
    margin-right: 250px;
    text-align: center;
    background: white;
}*/

b {
    color: #333;
}

.header h1 {
    font-size: 2.5rem; /*40px*/
    text-align: center;
    color: #595959;
}

/***************************/
/*  topnav                 */
/***************************/
.topnav {
    overflow: hidden;
    background-color: #333;
}

.topnav a {
    float: left;
    display: block;
    color: #f2f2f2;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
}

.topnav a:hover {
    background-color: #ddd;
    color: black;
}

a.active {
    background-color: #ddd;
    color: black;
}

/***************************/
/*  sidebar                */
/***************************/

/* .sidebar {
    overflow: hidden;
    background-color: #333;
} */

.sidebar ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
    overflow: hidden;
    background-color: white;
    position:absolute;
    height: 100%;
    width: 13rem;
    /* border-right: #000 1px solid; */
}

.sidebar li a {
    float: left;
    display: block;
    color: #000;
    text-align: center;
    width: 13rem;
    padding: 14px 0px;
    text-decoration: none;
}

.sidebar li:hover a:hover {
    background-color: #ddd;
    color: black;
}

li.active {
    background-color: #ddd;
    color: black;
}

/***************************/
/*  maincol                */
/***************************/

.maincol {
    margin-left: 14rem;
    margin-right: 14rem;
    margin-top: 2rem;
    min-height: 100vh; /* Ensure the body fills the entire viewport height */
}

img.author_pp { 
    width: 14rem;
    height: 11rem;
}

/***************************/
/*  footer                 */
/***************************/

.footer {
    padding: 2px;
    /*text-align: center;*/
    background: #ddd;
    margin-top: 20px;
    overflow: auto;
    color: black;
}

/* Pour les écrans de largeurs inférieures à 600 pixels*/
@media screen and (max-width: 600px) {
    .maincol {
        margin: 0;
    }
    /* .sidebar {
        display: none;
    } */
    .sidebar ul {
        position: relative;
        height: auto;
        border: solid 1px black;
    }
}