Thanks AndreaK22 and Tizz for the replies. Unfortunately I can still not get it to work.
Using Andrea´s method,the email field does not change width when I alter it from 40% and while your code changed the colour of everything else, the email field remained un colourable.
Tizz thank you too, I cannot get the methods to work either, there is no child theme either, just using the Modernize theme which has a controller which allows you to change the colour of the contact form, but again the email field is standing alone uncoloured and of the wrong size.
The code suggested by Biswajeet does not manage to control the email field either for some reason.
Looking like the only option is to deselect the html tags in the functions php file as suggested by author, but for some reason it is not allowing me to save it when I try.
Is there any way of just downloading the old pre update version of contact form 7, ie 3.3.3 ? Frustrating because it all used to work so well.