PHPWCMS uses page templates to determine the page layout (header, footer, menus etc.) for each category in the site structure. You can use the same template for each category (set it as the default), or you could create different templates and allow users to choose.
You can format templates using the 'default' CSS file - frontend.css - which can be edited from within the program, or you can create additional CSS files and place them in:
phpwcms_template / inc_css /
You (or users) could then choose a different CSS file to control each template. With this combination, you could certainly provide the ability to select different page layouts and colour styles. However there is no 'one-click' method for a user to select a site-wide theme... AFAIK.
