Using Custom styles in Configurator UI

You can define custom css classes in UI and use it anywhere in UI Element as style.

Add Raw text in the Page and add following in Text Expression. Notice the dot in beginning of class name. This is same as how you define style in standard HTML page using CSS.

<style>
.xxhighlight {
    font-weight: bold;
    background-color: yellow;
}
</style>

Now use above class in style class anywhere in UI element. You will only put xxhighlight in it.
Style = xxhighlight

You can learn more about adding custom style classes in google. You can add more attributes to classes as you want.

Now look and feel of customization and style will be limited to your imagination and not what Configurator UI is offering.