[roger64]

Indeed.

I join an ePub where I did test this. The body has a line-height of 140%.

There are some paragraphs, one sup tag for each paragraph. You can try the display with the value line-height:1; in the CSS or suppress it, or check it with line-height:0;

There are also two kinds of spans with which you can make the same kind of experiments.

For what I've found, the most reliable display is with the value line-height:1;

I tried it with Calibre 5.17. and Koreader.