html border box 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: border-box css

#example1 {
  box-sizing: border-box;
}

Example 3: box sizing border box

*{
 box-sizing: border-box;
 }