White background below custom dynamic mark so that bar line is partially hidden

[Claire Meyer]

Hi,

I have :

And would like something like :

My dynamic mark looks like :

dolcissimo = \tweak DynamicText.self-alignment-X #LEFT
#(make-dynamic-script
(markup #:normal-text #:italic "dolcissimo"))

Has anyone an idea of how to do that ?

Many thanks,

Claire