Go to set up/custom Styles and add your HEX colours below and test by generating a report

 

 

To change the body font this needs to be done in the DB:

No Teodor the CatSELECT * FROM _internal.Customer_Style_Active WHERE name = 'custom_font'

 

 

WARNING: 

This change will affect ALL reports so test on your own instance before testing on customer instance.