How can I create a full-width header in the Dawn theme?

[Reg101]

I used this code:
.banner__media {
height: 100vh !important;
width: 100vw !important;
object-fit: cover !important;
}

.banner–medium,
.banner–large,
.banner {
height: 100vh !important;
display: flex;
align-items: center;
}