A recent project had a requirementfor a style switcher allowing a visitor to control font size on the site as needed. (Many do not know how to change it through a browser, and most sites are not designed to allow for font size changes without completely trashing presentation.)
Because the project in question was a dynamic site I wanted to make a style sheet switcher that didn’t force a page reload and it seemed like most examples on the net required a page to reload with a new stylesheet. (After PHP or some other scripting language decided which css sheet to render the page with.) This meant additional calls to the server to repopulate data grids and other info, after re-running a query and parsing in PHP. To me this was truly unacceptable load on a server to simply change font sizes on a page.