The image below shows the options available for branding your candidate portal. Raise a ticket with the support team, or speak to your account manager if you are looking to rebrand your Kallidus Recruit candidate portal.
One extra thing to note: if your hero banner contains text, or images of people, where scaling on different screen sizes might make the text unreadable, or crop people badly, the size needs to be quite precise - 1600px x 500px (note for Kallidus - set "banner image height" to 30% for this to work).