Newbie question on sticky content menu

[pranaykotas]

I'm a newbie to Eleventy, trying to use this SSG for a non-profit think tank website. I want to know how does one enable the sticky left-side menu layout as is the case on this gov.uk page?

I essentially want a markdown article sub-headers to appear on the left as a sticky menu so that a reader can navigate easily.

[btrem]

You can use markdown-it anchor to automatically add id attributes to each heading. Then use eleventy toc plugin which provides a filter to generate a toc. Finally, use css to place the toc menu on the left, fixed, or whatever you want. (I didn't look at the gov.uk page, but I imagine you don't need specific css help.)