Improve the tab size in code samples

[svivian]

Example feed: https://gomakethings.com/feed/index.xml
Example article: https://gomakethings.com/styling-the-shadow-dom-with-css-variables-in-web-components/

In that article there are code blocks with tab indentation, however in NNW they appear as huge tabs (8 spaces) making it difficult to read:

In CSS this can be specified using tab-size: 4; . I could probably create a custom theme to do this but IMO it makes more sense to have a good default that all themes follow - I tried several themes and none of them set this.