Font size transformed incorrectly

[Kevin Muncie]

Version: Beginning in Calibre 5.15 continuing to latest 5.18 release
Operating Systems: Windows 10, MacOS 10.15.7

CSS `font-size: 19.28px` is being incorrectly transformed into `font-size: 120.5rem`

Testing has revealed this bug appeared starting in Calibre 5.15 when src/calibre/srv/fast_css_transform.cpp was introduced to speed up loading times.

This is a major breaking bug for any EPUB with this font-size and could possibly affect other font-size values. The EPUB is unreadable as the text is enlarged beyond any recognizable size and the EPUB will appear to not contain any text to the non-technical user.

I have attached a reduced test case of the sample EPUB3 spec from https://idpf.github.io/epub3-samples/30/samples.html with only a single line change, adding `font-size: 19.28px;` to the `body`.

[Kovid Goyal (kovid)]

Fixed in branch master. The fix will be in the next release. calibre is usually released every alternate Friday.

 status fixreleased

[Kevin Muncie (kmuncie)]

Thanks for the quick fix and slipping it into 5.19!

[Kovid Goyal (kovid)]

Note that because the result of the css transform is cached, you will
nee to use "Reload book" in the viewer controls to see the fix.