Changing the category navigation color
CSS code to change the layout of the category navigation.

These are the steps to add personalized CSS code to the design:

1. Navigate to Settings > Layout > Designer and launch the designer
2. Click Preferences (last icon) and enable Advanced
3. Click Customize CSS (penultimate icon)
4. Add the piece of CSS code at the bottom (copy and paste)

Publish the design (first icon in the designer window) to make sure the result is live.

The CSS code to customize the text for the category navigation:

#cat > ul > li a { color: #f00 }

It can also be done per item separately, this is for the first (1) item:

#cat > ul > li:nth-child(1) a { color: #f00 }

#f00 is red as an example, it can be any color.

The W3Schools website has a "color picker" for easy color selection:
https://www.w3schools.com/colors/colors_picker.asp

Learn more about HTML/CSS color coding:
https://www.w3schools.com/colors

Color Designer - easily generate color palettes
https://colordesigner.io

Color Combos - create color combinations
https://www.colorcombos.com