Happy to help! What comes to mind when I think about Vienna is its famous waltz. Quite difficult to master! Way more difficult in fact than what we're dealing with here 
Rendering a Delphi control is often done by converting it to a standard HTML control and then making adjustments to make it more Delphi-like. TWebEdit translates to <input>. TWebMemo translates to <textarea>. TWebComboBox translates to <select>. That sort of thing. And apparently a single TWebStringGrid translates to numerous nested <table> elements. This is of course how the web works - HTML at its most basic is just a set of elements on a page, after all. If you just work within the IDE, this really doesn't really matter and you can carry along quite happily without having to think about it much. But when you want to use CSS to do the heavy lifting of styling your app, or extending your app with other JavaScript libraries, then it matters a great deal.
So potentially a pretty big learning curve, but hopefully when people have questions they'll find helpful answers here that will shorten that up nicely. Please have a look at the Tips for New TMS WEB Core Developers post and try and add something to it that you've learned already that might help others facing the same learning curve, no matter how trivial. 
But the biggest question is whether you were able to accomplish what you were after? I've been thoroughly surprised and impressed that I've been able to do virtually anything I've set out to do with the stock TMS WEB Core components and CSS styling and a bit of JavaScript here and there. Way more flexibility and control (and development speed) than even what is possible from the VCL environment in many ways. So if you're struggling to do something, please make a new post about it. As a community, we'll all learn more and have better apps if we see these kinds of challenges and find ways to overcome them.