css calc function

1.class{
2	width: calc(50% - 20px);
3}

1.banniere {
2  position: absolute;
3  left: 40px;
4  width: calc(40px - 80px);
5  border: solid black 1px;
6  box-shadow: 1px 2px;
7  background-color: yellow;
8  padding: 6px;
9  text-align: center;
10  box-sizing: border-box;
11}
12

1.banner {
2  position: absolute;
3  left: 40px;
4  width: calc(100% - 70px);
5  border: solid black 1px;
6  box-shadow: 1px 2px;
7  background-color: yellow;
8  padding: 6px;
9  text-align: center;
10  box-sizing: border-box;
11}
12