Fix your browser/OS default font settings. This page have 0 styling and page with 0 styling should look perfect on your screen if you have everything configured correctly.
That page declares lang="zh" in the html tag. So it's probably not using the default font for Western or Unicode, but whatever the browser maps to Simplified Chinese.
In my case that was much uglier, and I had to fix it to read the page.
Looks good on firefox/ubuntu. It's strange that there's a browser using the lang tag for this; as I understand it web pages create a font spec according to style attributes and not lang tags, and fontconfig would only substitute fonts for a range of actual chinese characters if the preferred matching font didn't cover that range.
I saw the problem with Firefox 10 on CentOS. My default font was specifically configured to Bitstream Vera Serif.
Setting the default font in the Preferences seems to only change it for the encoding in the active tab (unless you go into the Advanced dialog). For several Asian languages it wanted to use "serif", which appears to be the 20-year-old X11 default version.