Stronger inline or individual component editing for sequence diagrams

[SaanchitaV]

Okay so recently I had to create a sequence diagram for a demo and I had to get it done quick so I used mermaid js instead of draw io because I did not want to waste time dragging and dropping or say erasing a participant and changing a lot of text by multiple clicks
I got done with the sequence diagram code in about an hour
But when I tried to do some inline styling I realized there are very limited options for component level styling
And Inline css classes also did not help

Examples -

I want to add additional text under an arrow (currently offers to add notes which is opaque and cannot be made transparent
I want to colour individual arrows
Change syntax or edit individual text instead of applying to the entire diagram
Add boxes around a set of steps instead of participants (And by boxes here I don't mean those with break, loop etc written - this message should be customisable)

This is what I intend to do in mermaid js
Here I have basically used the export PNG option and imported it in drawio and had to add those blue boxes
Would be helpful if this can be done as this one place would cater to everything diagram related then