CSS de caja fronteriza
#example1 {
box-sizing: border-box;
}
Southern Right Whale
#example1 {
box-sizing: border-box;
}header, ul, nav, li, a /* other elements */{
display: block;
-webkit-box-sizing: border-box;
-moz-box-sizing: border-box;
box-sizing: border-box;*{
box-sizing: border-box;
}* {
box-sizing: border-box;
}* {
-webkit-box-sizing: border-box;
-moz-box-sizing: border-box;
box-sizing: border-box;
}