I wonder if i can use the Kali linux default interface on Ubuntu. I just like the way that Kali linux look (it's black color on the top panel,icons,and more) way more than ubuntu looks. I've spent some hours of searching things like "Kali Linux default theme" but didn't find anything helpful. Is there any files or something that i can copy from kali into ubuntu to do that change ?
You should be able to copy the theme to Ubuntu.
Boot your Kali box and copy the themes from:
To your Ubuntu box using method of choice... a thumb drive will work for this.
Once the themes have been copied to
/usr/share/themes on your Ubuntu box, install and run gnome-tweaks:
sudo apt install gnome-tweaks && gnome-tweaks
Then simply select the theme copied from Kali.
I believe Kali uses Pure GNOME while Ubuntu uses a modified version of the same. So, in my opinion first step should be installing Vanilla GNOME.
If just copying over the theme doesn't work, you can install vanilla gnome with:
sudo apt install ubuntu-gnome-desktop
Then log out and select Gnome as your WM and then use gnome tweaks to select desired theme.