Inside the Toolbar & Logo panel
You have the ability to apply your chosen brand colour to the toolbar of all your docs by using the appropriate HEX code.
You can upload your brand logo in both colour and white - this will allow the themer to choose the appropriate version depending on the contrasting colour of the background it is sat on.
You have the option to edit the right margin space on the toolbar of your docs, which will allow you to apply the appropriate amount of clear space surrounding the logo. You can also edit the physical sizing of the logo itself.