Polsterung macht den Div -Überlauf
.div{
width: calc(100% - 20px - 20px )
height: calc(100% - 20px - 20px )
padding: 10px
border: 10px
}
Rian Jaro
.div{
width: calc(100% - 20px - 20px )
height: calc(100% - 20px - 20px )
padding: 10px
border: 10px
}