This modificator is usually used as an exception. I recommend to explore CSS specificity/priority/rules in google. It is quite big topic. For example you can use several parent or more specific selectors to override previous css selectors. Let me know if you don’t find this info after the search.
@Pandora_ramin All the times I have wanted to look at the code of your web something does not work or the link tells me page does not find. The few times I have been able to enter I find a different scenario. You have been constantly changing the codes so I can not help in that case because I can not restart the work every time you change the design.
I do not know what version OJS is using and I can not help you if you constantly modify the header design.
1.- You have version ojs 3.1.0-1 installed
2.- You have installed the Thema defaultManuscript.
2.- It seems that you made some modifications in https://disertante.com/revista/index.php/index3 (see image), but I can not find the codes you used to make the changes (maybe there are errors in the installation).
This is how your OJS installation looks:
This is how my OJS installation looks:
3.- On my server install a new version ojs 3.1.0-1. Also install the Theme defaultManuscript v.1.0.1
4.- The code to put the logo to the center and to show the menu below is this:
If you have applied modifications this code may not work.
If you want to see the working code, retype OJS 3.1.0-1, reinstall Theme defaultManuscript 1.0.1 (Release 1.0.1 · NateWr/defaultManuscript · GitHub).
You can then continue with the other changes for your site.
You should consider that I am not sure if the version of the theme defaultManuscript v.1.0.1 is compatible with the OJS version 3.1.0-1 (I am not currently using that theme). Maybe you can ask your creator (@NateWr) about compatibility.
I think you have installed a single journal and what you have posted is the home page of that journal.
But, @Pandora_ramin, seems to have installed two journals and what her link shows is the home page of the site, not the journal. Once you click any one out of two of her journals, I hope you will get home page of a journal which resembles yours.