UI - css: select source code without line numbers

[dna2github]

Is your feature request related to a problem? Please describe.
Currently in OpenGrok, when read some source code, if wanna copy/paste the code, I need to select some; but the selection always contains line numbers.

Describe the solution you'd like
I would like to have an option to enable: code selections without line numbers

1  hello world
2  this is a test

for example, above view, if i select 1st and 2nd line, I just want to copy hello world and this is a test without line number 1 and 2.

Describe alternatives you've considered
currently i can create a bookmark to invoke javascript to add a <style> tag with setting a.l a.hl span.l user-select: none to archive this.

Additional context
thank you

[vladak]

The '# Line' link near the top of the page can toggle line numbers.

[dna2github]

thx for the quick response.
yes, definitely your solution can resolve the issue like my alternative solution to invoke a bookmark javascript script.
there is a problem with your solution: when i toggle off the line numbers, i cannot know the line number i selected visibly.