contact form 7 styling issues

I am having problems with the recommended plugin contact form 7.
The error message shown when people incorrectly fill or miss a required field in the form overlays the actual text input field using the style applied by css class ‘.wpcf7 span.wpcf7-not-valid-tip’,in other words the text input area does not move down to make space for the error message which instead overlays the text input field or drop down menu and am not sure if this is something I have inadvertently done through some previous action or exists as a general problem.