styles.css

* {
    margin: 0;
    padding: 0;
}
body {
    background-color: aqua;
    background-attachment: fixed;
}
.nav {
    left: -200px;
     width: 200px;
     height: 100%;
     position: fixed;
     background-color: rgb(0, 0, 0);
     z-index: 3;
     box-shadow: 1px 1px #000;
     transition: left 0.3s ease-out;
}
.nav a {
    color: white;
    font-size: 1.5rem;
    padding: 15px;
    display: block;
    text-decoration: none;
}
.nav a:hover {
    color: black;
    background-color: aqua;
}
.nav button {
    margin-left: 160px;
    background-color: transparent;
    color: #fff;
    border: none;
    font-size: 1.9rem;
}
.nav button:hover {
    color: aqua;
}
.content {
    margin-left: 220px;
}
.content button {
    font-size: 1.6rem;
    padding: 15px;
}
.content button:hover {
    cursor: pointer;
}