Why is my stylesheet.css file not working correctly?
If you used a CSS editor/text editing program (Notepad is a well known "culprit" for this) which saves the file with a BOM (Byte Order Mark) WinCC OA can no longer apply that .css file correctly.
Please note: There is no log viewer message.
You can easily check if your file uses a BOM by validating it here: http://validator.w3.org/i18n-checker/check
Solution: Use a different editor(e.g. Notepad++) or deactivate the option that a BOM is used.