The size and shape of the font can be adjusted through visual themes, which are available in the 'EDIT' - 'Design' tab.
Each theme can be tailored to your needs. First, select the desired theme, and then click 'Edit' or 'Theme modification' on the top of the page. The theme editor allows you to change the size, color and typography of fonts for questions and answers, as well as the background color and frames. You can also insert your own logo.