Diffname in preview cards aren't bold anymore

[Kimitakari]

It used to be bold so that anyone could read the diffname but in the recent update they aren't bold.

[nanaya]

I changed that because it has been looking pretty bad and I find it more difficult to read. I'll let @arflyte decide on that.

[arflyte]

Keep it for now, I'll look into it again soon.

[RushFTK]

since arflyte already give conclusion, this issue might to close?

[peppy]

This issue is already assigned to him. It can remain open until it is either changed or deemed to stay the way it is indefinitely.