html, body {
    margin: 0;
    padding: 0;
    background: #fff;
    font-family: Helvetica, Arial, sans-serif;
}

body {
    display: flex;
    margin-left: 200px;
    height: 100vh;
    background-color: rgb(255, 255, 255);
}

/** NAVIGATION **/

nav {
    position: fixed;
    top: 0;
    bottom: 0;
    left: 0;
    background: white;
    width: 200px;
    height: 100%;
    z-index: 2;
}

nav > ul {
    list-style: none;
    margin: 40px -25px 20px 10px;
    padding: 0;
}

nav > ul > li {
    padding: 10px;
    cursor: pointer;
}

nav > ul > li[data-active="true"] {
    background: hsl(197, 37%, 24%); /* rgb(41, 53, 66) */
    color: #fff;
    border-radius: 5px;
}

/** MAIN **/

main {
    background: rgb(243, 243, 243);
    margin: 20px;
    padding: 20px;
    border-radius: 20px;
    width: 100%;
    height: calc(100% - 80px);
}