If this change happened today, most likely, you got a bad version of the site CSS.

If this situation was "always that way", you can change how the site is displayed using custom CSS in the Display Settings, or by enlarging the default font size your browser uses.

We do not use Javascript for the website here, especially not for automatically messing with settings that a user might want to set themselves. Javascript is far too great a vector for security problems, so I do not want to encourage its use where it is unnecessary.

Potentially, we could set up different screen layouts or font sizes using the @media selector, but so far, nobody has done so. For example, you could set up special hints for the browser if it thinks it is a low-resolution, low-input features browser:

@media handheld, projection, tv {
  #box { position: absolute; }
}
[download]

In theory, the same could also be done for large-browser environments:

<link media="only screen and (max-device-width: 480px)" href="iPhone.c
+ss" type="text/css" rel="stylesheet" /> 
<link media="only screen and (min-device-width: 1920px)" href="bigScre
+en.css" type="text/css" rel="stylesheet" />
[download]

... but just because I have a big screen does not mean that my browser takes up the whole available width of 1920 pixels.