Set tab size to 4 in Code views

Description / Overview

The tab size should be set to 4 instead of the default value of 8. This makes code containing tabs a lot more legible. Especially on smaller screens.

Use cases

Everyone who is sane and used to having a tab size of at most 4.... looking at you, Linux kernel

Links / references

https://www.w3schools.com/cssref/css3_pr_tab-size.asp Different prop for Firefox and Chrome

Feature checklist

(Make sure these are completed before closing the issue, with a link to the relevant commit.)