How to remove the gaps between highlighted lines?

Hi! So for time saving, I'll get to the point.

https://preview.redd.it/n48v0727aiyd1.png?width=928&format=png&auto=webp&s=cb0293725485a3ca84e015920b3faf08f94dcc08

You can see there are very small gaps between highlighted lines.

And this is when I use mouse to "black out" (idk how to describe it in English lol) the whole paragraph.

https://preview.redd.it/6bie4ortaiyd1.png?width=934&format=png&auto=webp&s=e7ed44f500f3b0dc10c0136585bf646e1193d9bd

You can see there aren't any gaps between lines.

So how can I make the highlighted lines look like that too? I know it might not be a big deal to you but doing this would help me a lot (as it looks more aesthetically pleasing and easier to read to me). Thanks!