Take this page for example (or any other page making extensive use of columns): EvoluData website revamp - draft contents - solutions index page
It has code that uses the Tiki FluidGrid module to automatically break it into columns, separated by "---".
However, when you use the arrow menu (top-right corner in the page contents, below the navbar) to click the "PDF" action, the resulting PDF has text that is correctly sized to the width of their planned columns, however the columns don't float/stack next to each other, so it ends up being one column "below" each other instead of "besides" each other, so you end up with a document that is much longer (and uglier) than it should.