The following tutorial covers changing diazo Chameleon Plone Theme columns width on a Plone 4.2 website.
Chameleon diazo theme has customizable columns width. Default left column width is 229px, default right column width is 200px.
You can change columns width via Diazo theme: Site Setup -> Diazo theme -> Advanced settings tab.
Note: For Diazo Support extension starting with 1.1b1 version, proceed to Site Setup ->Theming -> Advanced Settings tab.
Specify new values for columnonewidth and columntwowidth parameters.
Let's for example enter column one width 279, column two width - 150. Save changes and return to Plone Interface to view them: column one widened (from 229 to 279 px), column two narrowed (from 200 to 150 px).