Password protecting web page

I want to password protect a web page. I'm wondering if anyone would critique my approach.

An anonymous user would go to the page and a modal would open up asking the user to enter a password. I would of course not display any content at the back in case anyone decides to be clever and display:none; the modal.

Once the user enters the password, I would redirect and save a token as a cookie and check for that so that user wouldn't have to keep entering the password.

Just wondering if there are any security issues here aside from a personal physically accessing the computer and also if there would be any improvements that could be made.

I know I'm still being a little vague on some details, so let me know if there's anything important that I left out in regards to exact implementation.