You can wrap them inside a container div and use display:flex;
this way they will always be aligned to the vertical center of the container div.
.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;
}