The X-Corporation theme is nice but it is not totally responsive, the menu is not, the carousel is not, I was able to make the menu responsive for small screens using the good cookbook Now I have to see how can I fix the carousel with its captions.
I would suggest reviewing the themes before posting to Grav site for the sake of quality.
Regards
Joejac
@joejac, Reviewing themes (and plugins) would be a welcome addition.
Unfortunately, the devs can only do so much and your contribution would therefor be very much appreciated…
Since many themes are created by the community for the community, you might consider creating a pull request on https://github.com/tranduyhung/grav-theme-x-corporation to add your improvements to the repo. 
Hello @pamtbaau, I did the comment because the theme Deliver is very good, aesthetic, and responsive as well as other themes. I am not a developer, my son helped me, I do not know how to work with GitHub, can I post the code changes with the file name, here in this question forum?
Thanks to this post and this other post Keep collapsible menu open I got the idea to fix the mobile menu.
Regards
Joejac
@joejac, It’s not really useful to drop the changes here. The dev probably wouldn’t know if you did…
You could just try and go to github, sniff around, read some issues and maybe create an issue yourself sharing your findings with the dev.
Ok understood, I will post the changes in their issue system at least for the menu and carousel, so they will see if are convenient to include in their project, Regards.