After installing some different firmware versions, I got to the following results: In 1.7.3 some change was introduced, that makes some android apps displaying css-formatted pages, to lose formats such as bold or underline, but still retain others like italic.
Those apps display text properly with firmware 1.7.2, but in 1.7.3 and 1.7.4, when the page is displayed, it shows properly, but immediately it changes losing bold and underline, as I said above.
A good app to test this bug is the following:
https://goo.gl/csa5Si