<div class="boxes">
  <button>Button 1</button>
  <button>Button 2</button>
  <button>Button 3</button>
  <button>Button 4</button>
</div>

body {
  font: normal 16px/1.5 "Helvetica Neue", sans-serif;
  background: #1339AC;
  color: #fff;
  padding: 50px;
  margin: 0;
}

.boxes button {
  display: block;
  width: 100%;
  padding: 15px;
  border: none;
  margin-bottom: 5px;
  box-sizing: border-box;
  font-size: 1rem;
  text-align: center;
  text-decoration: none;
  background: gold;
  color: #000;
}

.boxes button:nth-of-type(even) {
  background: #e6c200;
}

.boxes button:focus {
  outline: none;
  color: #fff;
  background: firebrick;
}

@media screen and (min-width: 600px) {
  .boxes {
    display: flex;
    flex-direction: row-reverse;
  }
}