Flexbox is now supported in all major browsers and the spec is in Last Call Working Draft state. We utilize flexbox pretty heavily in our site and would love it if we could use it in Prince as well. It doesn't just make vertical centering easier but obsoletes a lot of other layout techniques and hacks.
We are beginning our investigation of CSS flexbox layout and would welcome any relevant example documents you might have. In particular there are questions of how page-breaking will interact with flexbox.
I desperately need flex support, we automate adding 1-3 logos to certificates for hundreds of organisations, and those logos are all different shapes and sizes. With our digital certificates we just use flex to have them all aligned in a horizontal row but this is a nightmare with floats.
What about getting support up for non-reflowing pages? I am using prince to create one page marketing items and that text doesn't need to reflow—which I am sure is one of the bigger problems you are trying to figure out with supporting flex—and having flex support for that kind of layout would be very helpful.
We're nearing completion of our testing for the first release of flexbox. To give you an idea of progress, at the present time we pass most of the relevant tests from the W3C public test suite with the remaining test failures falling under the following categories:
multicol flex items,
absolutely positioned elements in flex items,
poor performance for nested flex containers.
Please also note that we're not planning to support the following in conjunction with flexbox, at least in the initial release:
We ought to be able to release the first version by next month, assuming no major issues come to light. Please let us know if any of the features mentioned above are ones you might need, and thanks for your patience and support!
We've now got multicol flex items and absolutely positioned elements in flex items working properly, and we've also improved the performance of nested flex containers. We're planning to work on fragmentation later this year.
Please give it a try, and let us know what you think.
I've discovered an issue with margin:auto. When I have a single line item using flex with a margin-bottom:auto, flex works well for both the browser and export. However, when I increase the font size so that the line wraps to two lines, the margin-bottom: auto doesn't work any more on export even though the browser preview looks good.