Dolly, were you able to figure out a solution to this issue?

In order to find out the HTML color code for any color, open up the preferences file through MediaLab's option window. From here, navigate to the Fonts & Colours tab. If you select a specific area using either the combobox beneath the tabs, or through clicking an area on the sample layout, you will be able to edit that area. Select the item 'Questionnaire Background'. A color window should open up allowing you to select a new color. If you jot-down the Red, Green, and Blue values, you can use these to find the HTML hex color value. For example, in the default preferences file, the following values are used for the questionnaire background:

Red [204] Green [204] Blue [255]

Using these values, we now need to find an RGB to Hex converter. You can do so by using the web. Here's a site that I've googled that seems to work:
http://www.javascripter.net/faq/rgbtohex.htm

The output created for the above values gives: CCCCFF
Once we add a pound to the start of this value, we're ready to use it.

The final output would be as followed: #CCCCFF . In the future, we'll look into adding an easy conversion display for users who may need the hexadecimal values of an RGB color.

Let me know if this helps!