html, body, nav, div {
  margin: 0;
  height: 100%;
  width: 100%;
}
html, div {
  font-family: Arial;
  background-color: #eee;
  color: #444;
  user-select: none;
}
body {
  filter: brightness( 103.75% );
  font-size:1.5rem;
}
nav, div {
  display: flex;
  flex-direction: column;
}
div {
  outline: 1px solid #ddd;
  cursor: pointer;
}
div:hover {
  background-color: #0bb;
  color: #eee;
}
div:active {
  filter: brightness( 0% );
}
p {
  margin: auto;
  text-transform: uppercase;
}

@media( orientation: landscape ) {
  nav, div {
    flex-direction: row;
  }
}