Write a Theme

[ihkawiss]

Hello there

I'm currently writing a custom theme for roundcube as part of a project, the desired template is given as a HTML/CSS template. Because of that, I don't want to change any structure or css within the template. After a couple of hours with roundcube, I think that its necessary for me to change some parts of the core (php and js parts).

BUT, if I do that, I'll probaply have trouble updating roundcube next time 

So my question is:

1) Is there a way to override JS functions for example within list.js / app.js ?
2) Is there a way to override PHP core funtions ?
3) Do you think I'm really wrong ? What should be the correct way to develop the theme when HTML/CSS is already provided ?

Thanks

[SKaero]

Why don't you want to change the css, more like how do you plan to code a theme without changing the css?