fonts in kobo's webbrowser

Hi,

I'm from China , and you knew kobo doesn't support Chinese language.
With the folder "fonts" and my Chinese fonts in it , I can read Chinese e-book now . But the fonts doesn't work in the browser when Web pages contain Chinese .

Yesterday , I found that my Chinese fonts Works perfectly when the page has the css "text-shadow" property(like "text-shadow: 1px 1px 1px #ff0000;") .

So , what's the problem?
(my device is kobo glo 3.1.1)