Button Center CSS
Consider adding this to your CSS to resolve the problem:
button {
margin: 0 auto;
display: block;
}
I realize this is a very old question, but I stumbled across this problem today and I got it to work with
<div style="text-align:center;">
<button>button1</button>
<button>button2</button>
</div>
Cheers, Mark
Another nice option is to use :
width: 40%;
margin-left: 30%;
margin-right: 30%