aligning heading and subheading in `pkgdown` article table of content (TOC)

I am building a pkgdown website for my R package. Everything is working well, but one customization I haven't managed to figure out is how to align article headings and subheadings in a table of content (TOC).

In the image below,

• On the left: article from my ggstatsplot package website
  (https://indrajeetpatil.github.io/ggstatsplot/articles/web_only/effsize_interpretation.html)

• On the right: article from broom package website
  (https://broom.tidyverse.org/articles/adding-tidiers.html)

Note that the headings (red arrows) in the TOC in ggstatsplot article are all vertically aligned with the subheadings, while the TOC for broom article distinguishes between a heading and a subheading in terms of lateral separation. This is what I want but can't seem to figure out how to do.

In short: how can I turn the left TOC to look like the one on the right in terms of creating lateral separation between a given heading and subheadings below it?

Here is _pkgdown.yml for my package: https://github.com/IndrajeetPatil/ggstatsplot/blob/master/_pkgdown.yml

The following CSS rule should fix the indentation issue. You can add this to pkgdown/extra.css.

#tocnav ul ul {
    margin-left: 25px;
}

The CSS adds a left margin of 25px to any nested list under #tocnav. Adjust the margin size as needed. Targeting only the #tocnav is a conservative approach, but there may be other places in your pkgdown site that need this rule as well.