how to create multiple box in html using sing box code code example
Example 1: box sizing border box
*{
box-sizing: border-box;
}
Example 2: how to style rule to apply the Border Box model css
header, ul, nav, li, a /* other elements */{
display: block;
-webkit-box-sizing: border-box;
-moz-box-sizing: border-box;
box-sizing: border-box;