Columner is a Firefox addon, make a web page thinner for comfortable reading, allows you to control it with F + mouse wheel or Shift-Alt + U/L keys. This can be useful to make text more readable, especially on wide screens.
After installation, open add-on options and set the way you like to control a width of web page: with mouse wheel or/and with keys.

Requirements:
* Firefox

The license of this software is Free, you can free download and free use this browser plug-ins software.