[retiredbiker]

The answer, as you hint in the last line of your post, is in styles - paragraph styles, to be specific.

99.999% of your text in Writer should be controlled by paragraph styles. Only short bits of italic or bold should be done from the toolbars.The paragraph styles will control spacing between paragraphs, indentation, and everything else. The style settings will become the css controlling the ebub that Calibre will convert to.

Part of this, of course, is do not ever use blank lines (i.e. hitting "enter") for spacing in Writer. Set the spacing you want in a paragraph style. Likewise, no tabs or spaces for indentation. If there are no intelligent style settings in the text, conversion has almost nothing to work with.

How do you edit a paragraph style? One easy way to get there is right click on a paragraph in Writer, go down the menu and select "paragraph", then run down again and hit "edit style" at the bottom. You will get a panel like the attachment, where you can control---everything, for that style.

You can find all sorts of tutorials for using paragraph styles by simple searching. And spend a while exploring the Styles menu.

They styles that come with Writer are OK for some types of documents, but you will probably want to make a few custom ones for your particular needs. The LO help system is also really good with Styles.