Answers for "how to center button in div"

button center bootstrap

<div class="text-center">
	<button type="button" class="btn btn-primary">My button</button>
</div>

html center button

button{
    /*Change the width as much as you like, but make sure 
    margin-left and margin-right + width = 100%*/
    width:50%;
    margin-left:25%;
    margin-right:25%;
}