Section headings hidden when linked

[cbandy]

When I follow a link to an h3 section heading in Chrome or Safari on macOS, the heading is hidden behind the top navigation and it's not clear to me where I should start reading.

For example, when I click postgres-operator/.../#customizing-pgbackrest-via-configmap I see:

screenshot of current behavior

I would prefer to see something like the following:

mockup of desired behavior

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Links to h2 section headings seem to behave as I'd like. For example, when I click postgres-operator/.../#custom-annotations I see:

screenshot of related behavior