Why does the preview function in design tools when i develop need modules not render the correct css?
If there are some generic CSS classes (i.e. “container”) in the module’s HTML that are found in an external style sheet (not in the module’s CSS), the preview will not render it properly.
You can try one of these options (2 or 3 would work best):
1) attach the external CSS to the module to see if that shows up better in the preview mode
2) add the module to a template and preview the template
3) create a page, then add that module to the page