In the theme settings, you can edit the color palette:
I’m unsure why there is this CSS. You can overwrite it in a theme component:
.navigation-categories .search-banner {
padding: 0
margin: 0;
height: auto
}
This is how the theme uses CSS for that specific banner.
You can adjust it to your needs.
.custom-search-banner-wrap {
background: linear-gradient(
270deg,
var(--tertiary-medium) 0%,
var(--tertiary) 100%
);
}
Useful links:
