Actually setting the CSS Property font-weight
to normal
kind of fixes the thing when the font size is small enough. It seems that bootstrap was kind of messing with my font.
For example :
<label>
<input type="checkbox" name="checkbox" id="notify-on-message" />
New Message
</label>
Was creating a blurred font. After applying style="font-weight: normal;"
to the label the font was not blurred anymore, both in Firefox and Chrome.