AnchorJS links are always visible since 2.56.5

[kleisauke]

Operating System: Windows

DocFX Version Used: 2.56.6 (regressed since 2.56.5)

Template used: custom template (most things are inherited from the default template)

Steps to Reproduce:

1. Visit:
   • https://kleisauke.github.io/net-vips-tests/api/NetVips.html (DocFX 2.56.2)
   • https://kleisauke.github.io/net-vips/api/NetVips.html (DocFX 2.56.6)
2. Notice that the AnchorJS links () always appears to be visible for the second URL.

Expected Behavior:
AnchorJS links only become visible when hovering over the headings.

Actual Behavior:
AnchorJS links are always visible.

Notes:
This seems to have regressed since 2.56.5, most likely due to PR #6717.