body {
  background-image: url("images/concrete.jpg");
}
.button {
display: inline-block;
  width: 80px;
  height: 30px;
  line-height: 30px;
  background: gray;
  margin: 0 4px;
  text-align: center;
}

.container{
  display:flex;
  flex-direction:row;
  align-items:center;
}