Originally Posted by cybmole
I am a little puzzled as to how these margin top, margin bottom values work, when set in CSS
I have experimented with altering definitons for the calibre css that applies to p tags ( in sigil) & then viewing the results in calibre viewer
i find that non=zero values generate blank lines as per the table below (values in ems)
top = 0, bottom = 0 : no blank lines
top = 1, bottom = 0 : 1 blank line
top = 0, bottom = 1 : 1 blank line
all that makes sense
then comes top= 1, bottom= 1 - I expect to see 2 blank lines but I only see 1 ???
continuing top =n>1, bottom = 0: n blank lines OK
I've not done top=n, bottom=m (n,m>1) to see if I get n+m blanks, or something different. I would have expected n+m blanks but the 1+1 result has thrown me
it is only the 1+1 that is an apparent anomaly
what am I not understanding correctly here please ?
PS I forgot , in this test, to check what happens when both margin top & margin bottom explicit definitions are both removed - I think from past experience that causes p tags to default to just 1 blank line - above or below - not sure which ?
once I get this straight in my mind, I'm thinking of having some global extra css code to hand ( for my default preferences) that lets me easily flip between the various look n feel options currently begin debated & polled elsewhere i.e. indent + no blanks, indent+ blanks, no indent + blanks.
the existing calibre options do some of that already, but not all of it.
AM I right in thinking that can all be done with calibre overrides rather than having to open book & edit CSS ? if so, than I guess this is headint toward suggesting an enhancement to C. look n feel options - where you tick one of 3 ( or more ) predetermined layout styles ( indent + blanks settings) and the book is converted to that presentation for you.
Ultimately it could be a buttom on the e-reader device that enables this. (Kindle already has line spacing, font spacing & words per line user settings )
No 0 values need UNITS. I use EM, which scales with Zoom (at least, within EPUB)
They are adjacent ('boxes', in the box model): Bottom: 1em (para#1), top: 1em (para#2) get added for a total of 2em between paras 1 and 2.
You play 'stack the blocks'
Link to w3schools box model