body {
    font-family: Arial, sans-serif;
    letter-spacing: 1px;
}
header {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 500;
}
.hamburger-menu {
    display: flex;
    flex-direction: column;
    justify-content: space-around;
    width: 30px;
    height: 25px;
    padding: 8px;
    border-radius: 3px;
    background: rgba(0, 0, 0, .5);
    cursor: pointer;
}

.hamburger-menu .bar {
    width: 100%;
    height: 3px;
    background-color: white;
}

.menu-overlay {
    display: none;
    opacity: 0;
    position: fixed;
    top: 0;
    left: 0;
    z-index: 10;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, .7);
    transition: opacity .5s;
}

.navigation {
    opacity: .9;
    position: fixed;
    top: 0;
    left: -100%;
    z-index: 20;
    width: 80%;
    height: 100%;
    background-color: white;
    transition: left .5s;
}

.navigation a {
    display: block;
    padding: 10px;
    border-bottom: 1px solid #dddddd;
    color: black;
    font-size: 4vmin;
    text-decoration: none;
}

.navigation a:hover {
    background-color: #f0f0f0;
}