style.css

html, body {
    width: 100%;
    height: 100%;
    padding: 0;
    margin: 0;
    overflow: hidden;
}

section, header, footer, nav, div, span, ul, li, a {
    box-sizing: border-box;
}

header {
    position: fixed;
    top: 0;
    right: 0;
    left: 0;
    background-color: #f2f2f2;
}

header nav {
}

header ul {
    margin: 0;
    padding: 0;
    list-style: none;
}

header ul li {
    display: inline-block;
    padding: 0 20px;
}

header ul a {
    font-weight: 700;
    text-decoration: none;
    color: #4d4d4d;
    height: 50px;
    display: block;
    position: relative;
}

header ul a span {
    position: relative;
    top: 50%;
    transform: translateY(-50%);
    display: inline-block;
}

section {
    float: left;
    display: block;
    height: 100%;
    padding: 75px 0 0 0;
    margin: 0;
}

#section-section1 {
    background: #2c3e50;
}

#section-section2 {
    background: #16a085;
}

#section-section3 {
    background: #27ae60;
}

#section-section4 {
    background: #c0392b;
}

.horizon-prev, .horizon-next {
    position: fixed;
    top: 50%;
    margin-top: -24px;
    z-index: 9999;
}

.horizon-prev {
    left: 20px;
}

.horizon-next {
    right: 20px;
}