Select variating position NTH child with CSS - html

Question

I have an item (X) in a menu that changes the position depending of the user, for example:
Regular user:
N | N | N | X | N
Admin User:
N | N | N | N | X
I need to select that item using NTH-CHILD, the item has no ID or CLASS or any fields, this needs to be done using NTH-CHILD, so using the first example to select the item in a regular user menu:
element:nth-child(4)
But this instead should work for both cases in a single selector
element:nth-child(4 or 5 will always be the same with the algorithm)

Answer 1

Selectors match elements based on information relayed by the markup. This information does not include text content. That's why Johannes and dippas have suggested adding the appropriate class names to the body or some other element — because that's precisely the sort of thing classes were meant for.
If your markup does not discriminate based on whether the user is a regular user or an administrator, then as far as CSS is concerned, your markup is identical in either case, and there's nothing you can do to ensure that your selector always matches the right element.

Answer 2

If you have the possiblity to put different classes into the body tag (or any other tag that is on a higher level) depending on the status admin/not-admin, you could adress it this way:
.user-page ... element:nth-child(4), .admin-page ... element:nth-child(5) {
...
}

Answer 3

there has to be something to differentiate the regular user from the admin user, usually is a class added to html or body tag, if you have that, then you could use the nth-child or nth-of-type based on the parent.
Something like this:
(used section for snippet/demo)
div {
background: green;
display: inline-flex
}
.regular div:nth-of-type(4) {
/* nth-last-of-type(2) */
background: red
}
.admin div:last-of-type {
/* or nth-of-type(5) or nth-last-of-type(1)*/
background: red
}
<section class="regular">
<div>normal</div>
<div>normal</div>
<div>normal</div>
<div>NOT normal</div>
<div>normal</div>
</section>
<hr />
<section class="admin">
<div>normal</div>
<div>normal</div>
<div>normal</div>
<div>normal</div>
<div>NOT normal</div>
</section>