Preview display is good, both the question and the answer input box are large size.
BUT
When I actually study the deck, the answer input box is still the smaller default size.
Input text-align works, but font-family and font-size are broken.
I’m not an expert by any means, but usually when I have an issue with styling previewing correctly, but then not being implemented, I try adding !important after it.
I copied your styling with a basic typing deck, and changing font-size: 100px; to font-size: 100px !important; seemed to work for me. You had everything correct, but the styling was getting overwritten somewhere afterwards.
While Front preview and Back preview are okay, and Study Front display is okay, after I fill in text and Show Answer, the font size on back is still small.
After checking with a WebView inspector, I think the reason you need to use !important on the front side is because the default styling is defined inline and thus takes the precedence.
Since the styling is assigned not to the element itself but to the parent div, it can be overriden even without using !important.
Also, as you can see, there is no input element on the back of the card, and this is why using input as a selector did not work.
EDIT: on second thought, the following code should work both on the Front and the Back side of the card (you can just replace the input selector in your code with #typeans)