How to hide the site identity?

Hello, i am currently working on a site (still local so i cant share it with you guys)
But I want the site idenity to show up in the browser tab, however i dont want the text to be fixed in the top left corner of my site. It also makes the menu bar really big, which isn’t nice.
I have read some other topics about adding code to hide the site identity and subtitle, however it never works. I have tried to add the CSS in the ‘Add CSS’ menu of the Airi theme itself. I have downloaded the ‘Simple Custom CSS’ plugin. But neither of them work.

The code im trying to add is either:
.page .hentry .entry-header {
display: none;
}

or

.page header.entry-header {
display: none;
}

None of these work, so i would really like some help with this.

Alright this looks stupid, but ive found another topic about this question. The thing that solved is to add the following code to ‘add extra CSS’ menu:

.site-title,
.site-description{
display: none;
}