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

section {
  float: left;
  display: block;
  height: 100%;
  padding: 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; }