[cybmole]

the language is css.
end each bit with ; each definition goes in {}
usually each section is a new line, but your code may work as-is

I would use 3 lines like so

body { orphans: 1; widows: 1; }
div, p , blockquote {line-height: 1.0}
page { margin-bottom: 5pt; margin-top: 5pt }

actually I'd leave out that line height stuff, it will either do nothing & make lines look squashed, I reckon.
and if you set line height within the book, you cannot then use the reader's slider control to override.

my own kobo extra css file looks like this:
@page {margin-top: 12pt; margin-bottom: 0:}
body { orphans: 1; widows: 1; }
body {adobe-hyphenate: none;}