Revisit text-formatting styles

[mejedi]

Text styling in docs generally doesn't look great.

Styles must use em units, enabling sharing the greater part of the stylesheet between desktop and mobile and scaling everything proportionally (#79).

Currently open issues labeled design

• Improve documentation design #9, Mobile version: bugs #58

Basics

• line spacing is too small; line-height: 1.4 looks better
• normal text is too light, emphasised (bold) text stands out too much
• section headers don't stand out enough
• move to text-decoration: none links (no underline)

Vertical spacing between blocks

Vertical spacing is an important tool, separating different blocks of information while retaining visual consistency.

• vertical spacing before section header should noticeably exceed a regular inter-paragraph gap
• vertical spacing before and after bullet list and enumeration, as well as the gap between list items, should be consistent with an inter-paragraph gap
• vertical spacing around embedded table or a block of code should be consistent with an inter-paragraph gap as well
• sometimes the spacing just gets odd
• spacing around note/error [scroll up after following the link] blocks is too small, especially if a section header follows

Horizontal indentation

• horizontal indentation in bullet lists and enumerations is wrong — the bullet must move further to the right; currently it is in line with the left text margin
• function description bodies should be indented further to the right (see how Python docs do it)

Misc

* tables often need more breathing air