APM logon customization

Hi all,

Would someone be able to help me with customizing the APM logon page to something like the below picture.

I have an HTML code for my display but struggling to understand the format of the APM_FILL.CSS file where these settings are stored.

Is there a section in there that is dedicated for HTML or does it require another language?

Any guidance is appreciated.

 

Admin update: adding image inline for simplicity