Can a reusable element like a header nav show text data from the current page?

[petter]

One common way to exchange information between reusable elements and the page, is to use a state on the reusable element. What you can do in this case is to set up a custom state of type LEAD on the Reusable Element, and on the page load of lead_details, you set this custom state to the Lead loaded on the page.