A set of rules that will improve your typography 10x.

Use Traditional Point Sizes

Display     Double Canon    4.666
Heading 1   Canon   3.999
Heading 2   Double Great Primer 2.999
Heading 3   Double English  2.333
Heading 4   Double Pica 2.000
Heading 5   Paragon 1.666
Heading 6   English 1.166
Body        Pica    1.000
Fine Print 1    Small Pica  0.916
Fine Print 2    Bourgeois   0.750

Use Serif for Italic Text

Reduce Heading Spacing

The spacing between a heading and a paragraph should be less than the regular paragraph spacing. If regular paragraph spacing is used instead, the heading would seem too far away from the paragraph.

Use Thin Space

Thin Space might be the most underrated HTML entity. It can be used for a name like J. K. Simmons. Without spacing, the J and K would seem too close together; with a regular space, they seem too far apart. Insert a thin space and it is just perfect.

The HTML code is  . You can go even further with Hair Space  

Don’t Use Helvetica, Inter, & Roboto