I've set some styles in a Survey123 Connect form, just a simple text color and toolbar background color, but they do not apply to the web form when I publish the survey. I also can't change them at survey123.arcgis.com because "editing a survey published by Survey123 Connect is not supported." I can't find any other mention of this problem in "Known Issues" or on GeoNet.
EDIT: I tried setting colors for all the options and found the following:
Setting 'Text Color' has no visible effect on anything
Setting 'Background Color' works as expected.
Setting 'Toolbar Background Color' changes the background color of the body of the html page.
Setting 'Toolbar Text Color' has no visible effect on anything
Setting 'Input Text Color' works as expected.
Is there a different way to upload or create a web form from an XLSForm that will retain these settings?