How to set width of mirror line in plotly js

Hello everyone,
I have a situation where I am setting linewidth property to some value and also using mirror key as true.I am expecting same line width for axis line as well as mirror line. But mirror lines are always getting a little more width and is pretty much evident .

So why mirror lines are taking little more width than their axis lines ? And how to make sure to have equal line width for both.

Any help will be appreciated.

Sounds like a bug. Can you share a reproducible example?