.nav-btn {
  font-family: "Arial", sans-serif;
  background-color: transparent;
  color: white;
  position: fixed;
  height: 2em;
  padding: 0 12.5px;
  border: 1px solid white;
  outline: none;
  font-size: 1.2em;
  z-index: 10;
}
.nav-btn:hover,
.nav-btn:focus {
  background-color: white;
  color: black;
  outline: none;
}
.nav-btn:active {
  background-color: red;
  color: white;
  border-color: red;
  outline: none;
}
.nav-btn-top {
  top: 25px;
}
.nav-btn-bottom {
  bottom: 25px;
}
.nav-btn-prev {
  left: 25px;
}
.nav-btn-next,
.nav-btn-end {
  right: 25px;
}

.instruction {
  font-family: "Arial", sans-serif;
  color: white;
  position: fixed;
  left: 12.5%;
  bottom: 1.25%;
  width: 75%;
  font-size: 1.25em;
  line-height: 110%;
  text-align: center;
  z-index: 10;
}