Disclaimer: Please note that using CSS to customise the styles used by the Sonia web applications is outside the scope of Sonia Support, and you do so at your own risk.
To change the styles used in the Sonia web applications, you need to use something called Cascading Style Sheets (CSS) which is used to describe the presentation of web pages.
With CSS, you can control the colour, font, the size of text, the spacing between elements, how elements are positioned and laid out, what background images or background colours are to be used, different displays for different devices and screen sizes, and much more!
The attached document will cover several scenarios as examples using CSS. This guide is certainly not definitive and there are many more applications, but the intention here is to provide a starting point.