By default, there is a light theme applied to the website.
If you prefer a dark mode, or add a splash of colour, you can change the colour scheme.
Beside Account, you will see a paintbrush 
, click it and choose a look.
The icon will pulsate letting you know it is being applied, and the page will refresh with the new look.
If you have any questions, feedback or suggestions, please let me know!
