@elipsett, thank you very much for provided snippets!
I added following code to page_styles.css of several ePubs converted from azw3 and now they are vertical!
Code:
.hltr {
writing-mode: horizontal-tb;
-webkit-writing-mode: horizontal-tb;
-webkit-writing-mode: horizontal-tb;
}
.vrtl {
writing-mode: vertical-rl;
-webkit-writing-mode: vertical-rl;
-webkit-writing-mode: vertical-rl;
}
I wish if Calibre would start adding this snippet to all converted ePubs by default.