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[x] bug report => search github for a similar issue or PR before submitting
[ ] feature request
[ ] support request => Please do not submit support request here, instead see https://github.com/angular/angular/blob/master/CONTRIBUTING.md#question

Current behavior
Search bar from topnav bar is visually on top of the sidenav drawer and accessible.

Expected behavior
Search bar should be visually behind the sidenav drawer and accessible only when sidenav is closed.

Minimal reproduction of the problem with instructions
Open sidenav drawer using hamburger menu in Docs in mobile view.