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Turtle91 · 11-09-2024, 08:23 AM

Short answer: no. ePub 3 does not automatically devolve into ePub 2.

Good news is that you can create your css to take advantage of the ePub standard which requires that unknown css must be ignored gracefully. So, you put your ePub2 styling first, then include your ePub3 styling after (closer to the bottom) on your stylesheet. If it doesn’t understand (or support) your ePub3 styling then it reverts to the most recent settings it DOES understand (the ePub2 styling). This is referred to as ‘fallback coding’.

Unfortunately some of the older, but still common, devices have a bug in which they completely throw out the entire css stylesheet if there is something it doesn’t like on it - VERY frustrating! @Rbnjrg posted a technique he uses to work around this bug - you can search for the very recent thread (sorry I’m on my phone or I would link it).

Rbnjrg’s method is to use a simple JavaScript which is only supported by ePub 3 devices. If it supports ePub3/js then the script links a second, ePub3, stylesheet. Older, ePub2 only, devices won’t run the script and will never ‘see’ the ePub3 styling.

Have fun with the new book format!

11-09-2024, 08:23 AM	#2
Turtle91 A Hairy Wizard Posts: 3,355 Karma: 20171571 Join Date: Dec 2012 Location: Charleston, SC today Device: iPhone 15/11/X/6/iPad 1,2,Air & Air Pro/Surface Pro/Kindle PW & Fire	Short answer: no. ePub 3 does not automatically devolve into ePub 2. Good news is that you can create your css to take advantage of the ePub standard which requires that unknown css must be ignored gracefully. So, you put your ePub2 styling first, then include your ePub3 styling after (closer to the bottom) on your stylesheet. If it doesn’t understand (or support) your ePub3 styling then it reverts to the most recent settings it DOES understand (the ePub2 styling). This is referred to as ‘fallback coding’. Unfortunately some of the older, but still common, devices have a bug in which they completely throw out the entire css stylesheet if there is something it doesn’t like on it - VERY frustrating! @Rbnjrg posted a technique he uses to work around this bug - you can search for the very recent thread (sorry I’m on my phone or I would link it). Rbnjrg’s method is to use a simple JavaScript which is only supported by ePub 3 devices. If it supports ePub3/js then the script links a second, ePub3, stylesheet. Older, ePub2 only, devices won’t run the script and will never ‘see’ the ePub3 styling. Have fun with the new book format!