word-wrap break-word does not work in this example

Mozilla Firefox solution

Add:

display: inline-block;

to the style of your td.

Webkit based browsers (Google Chrome, Safari, …) solution

Add:

display: inline-block;
word-break: break-word;

to the style of your td.

Note: Mind that, as for now, break-word is not part of the standard specification for webkit; therefore, you might be interested in employing the break-all instead. This alternative value provides a undoubtedly drastic solution; however, it conforms to the standard.

Opera solution

Add:

display: inline-block;
word-break: break-word;

to the style of your td.

The previous paragraph applies to Opera in a similar way.