aligning submit button in the middle of the coloumn code example

Example 1: 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%;
}

Example 2: input type submit align center

<input type="text" style="margin:0px auto; display:block;" />