Keep the shared header blur treatment while removing the horizontal rules drawn by the global chrome, channel header, and top chrome backdrop.
Co-authored-by: Cursor <cursoragent@cursor.com>
Render a single full-width backdrop strip behind the inbox pane headers
instead of a per-pane backdrop-filter box. The blur now samples
continuously across the column boundary rather than clipping at each
pane edge. Inset headers become transparent and share a measured height
via a new CSS variable so the strip spans both columns.
Co-authored-by: Cursor <cursoragent@cursor.com>
