Bootstrap/site/_includes/skippy.html

<div class="skippy overflow-hidden">
  <div class="container-xl">
    <a class="sr-only sr-only-focusable d-inline-flex p-2 m-1" href="#content">Skip to main content</a>
    {%- if page.layout == "docs" -%}
      <a class="sr-only sr-only-focusable d-none d-md-inline-flex p-2 m-1" href="#bd-docs-nav">Skip to docs navigation</a>
    {%- endif -%}
  </div>
</div>