How to set space between text lines ?

How to set space between text lines ?
I have a text style in a css file, can I set the space between lines here? or
do i need to set that generaly on whole page from page properties or something ?

I am interested in that space that appears when text goes to next line by
itself while typing and there is another space when you press enter to go to
next text line, those 2 spaces betwen lines have diferent sizes, how can i set
them ?

Thanks.
Adrian.