Is it possible to change the colour of a combo box based on it’s content using CSS only? See image below, I want to change this to a specific colour if it has the word YES inside it using only CSS?

The reason I can only use CSS is because the vendor of this web based system only allows for stylesheet changes/customisations via the frontend.

I have managed to at least change the entire combo box colour regardless of content as a last resort option using the following CSS, any help would be much appreciated:

#ctl00_ctl00_contentPlaceHolderRoot_TaskSelectorsPlaceHolder_ctl00_autoCompleteLoc_comboBox{
background-color: yellow;
}