<button type="submit" class="btn">Add to Basket</button>

<button type="submit" class="btn border">Add to Basket</button>

body {
  padding: 0;
}

button {
  display: block;
  margin-bottom: 20px;
  -webkit-box-sizing: border-box;
  &.btn {
    padding: 30px;
    width: 200px;
  }
  &.border {
    border: 2px solid red;
  }
}