style.css

* {
    box-sizing: border-box;
}

body, html {
    height: 100%;
    margin: 0;
    background: black;
    color: white;
}

.wrapper {
    height: 100%;
    max-width: 600px;
    margin: 0 auto;
    position: relative;
    padding: 100px 20px;
}

.drilldown__container {
    overflow: hidden;
    width: 300px;
}

.drilldown {
    position: relative;
    width: 100%;
    font-family: 'Century Gothic', sans-serif;
}

.drilldown__sub {
    display: none;
}

.drilldown__sub--active {
    display: block;
    position: absolute;
    width: 100%;
    top: 0;
    margin-left: 100%;
}

.drilldown__back {
    font-size: 24px;
    margin-bottom: 36px;
}

.drilldown__item {
    font-size: 30px;
    margin-bottom: 20px;
    display: block;
}

a {
    color: white;
}