What are you actually trying to achieve here, your own custom login/signup lightboxes?
First off, note that there are three types of login/signup of which you will want the Corvid option
https://support.wix.com/en/article/about-the-member-signup-form#corvid-form
Wix do a Corvid example for a form, which you can find here.
https://support.wix.com/en/article/corvid-tutorial-creating-a-custom-registration-form-with-code
Note, that if you do use Corvid for this, then you will need to change your member signup settings to suit your choice as shown here.
https://support.wix.com/en/article/corvid-enabling-custom-site-registration
If you want to have a members profile page, then this tutorial is a good option as it will let you make up a page that lets user login and logout and direct them to their member profile page.
https://support.wix.com/en/article/corvid-tutorial-building-your-own-members-area
Of course you can change this page to suit your needs and change the example to go to another page on your site.
However, note that if you direct your user to a new page after logging in then this example will work.
If you want the user to stay on the same page, then you will need to refresh the page after the user has logged themselves so that the page code will be worked again and make the members only parts of it change.
If you stay on the same page and don’t refresh the page after login, then the user will be logged in, however the button on the page will not change from login to logout and any member only elements set to be shown only when the member is logged in, will stay hidden to members.
Finally, there are other examples for login/signup through lightboxes and Corvid as shown here from Nayeli (Code Queen).
Wix Member Login - How to customize member login on Wix using Wix Code
https://www.totallycodable.com/wix/corvid/custom-registration-for-site-login-using-wix-code
Wix Custom Registration to Check Existing User and Input Validation
https://www.totallycodable.com/wix/corvid/corvid-registration-code-check-existing-user-and-input-validation
Nayeli has also done a tutorial for the Wix Members Profile tutorial that you may want to watch too.
2017 Create Member Profile Log In Page - Custom Private Client Member Dashboard - Wix Code
Updated version here.
Creating a client dashboard in Wix using Wix Code
https://codequeen.wixsite.com/membership-dashboard