You can also try to open these website directly from Kindle.
If you find it too small, you can try to play around with some browser settings like
<kindle:setting name="minimumFontSize" value="0"/>
in /var/local/mesquite/browser/config.xml (change this value from 0 up to 9)
However, after a reboot all setting will set to default, unless you change a squashfs content.
Details are given in
this forum.