*{
  margin :0;
  padding:0;
}

.header{
  min-height: 100vh;
  width: 100%;
  background-image: linear;
  gradient(rgba(4,9,38,8.7),rgba(4,9,38,8.7)), url("https://i.pinimg.com/1200x/15/89/f9/1589f9ec52f325ea5dbc87ed39a86456.jpg");
  background-position: center;
  background-size: cover
  position: relative;
}