Styling with CSS

Select the Code tab, and create a new class called myClass, i.e.

.myClass {
   color:blue;
}

Save your resource and click the Design tab, where you'll see your new class and its properties. 

Go to Web Resources in your presentation template, open Style Sheets and add your myStyles CSS resource. Save the presentation template.

Go to your form, drag and drop a text control onto a page and add some text.

Open the Control style on the right hand side of the studio. 

Go to Advanced properties then Style. At the bottom of the window, select Enable local setting and click the elipsis [...] to view your available CSS tags.

Select your class and click the arrows [>>] to add it to your Selected classes. Click ok and exit the window.