Before you start designing Voice of the Customer for Dynamics 365 surveys, you'll want to define one or more themes to use to match your company's style. Themes define the color scheme for your surveys. You can design multiple themes if you want to use different ones for other surveys.
From the menu, go to Voice of the Customer for Dynamics 365 > Themes.
Click New. Or, if you want to edit the default theme, click Default in the list of themes.
Fill out the Name field.
Adjust the survey’s color values by specifying the hexadecimal value for each part of the survey (for example, the hex value for blue is #0000FF). w3schools provides a handy reference chart for hexadecimal color values. Click a hex value in the chart to see a chart with corresponding RGB values (for example, the RGB value for blue is 0, 0, 255).
If you want, add custom CSS instructions under CSS.