fixed avatar and message box layering (#8190)
fixed avatar and message box layering (#8190)

Co-authored-by: Andy Balaam <7f18c8a69fea12e31941e02d4010c6c156711d98@element.io>
matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk