Add (custom) JS modal/banner to website

I want to add a CUSTOM modal/banner to our Kentico site.

I believe it is currently running Kentico 10 (upgrading to v12 soon I was told)

This is for a cookie notice banner/modal.. (we do not want to use any of the built on Cookie Law/Simple Cookie Law approaches)

There are several parts to this.. and I'm not sure where they all go.. and how to link them together.

1.) The actual .js script/code. - I have added that as 'cookie_notice.js to the javascript section, and is has path of:

~/CMSScripts/Custom/cookie_notice.js

https://www.somedomain.org/CMSScripts/Custom/cookie_notice.js

2.) The .css that styles the cookie notice banner (and places it at the bottom/above the footer on a higher z-index)

3.) The actual 'mark-up (HTML) content (not sure where this needs to be added/created? nor how to link/add it to the site so that it shows on the site when a user loads the URL)

• Not very experienced with Kentico, so please do not respond with things like: just make a 'xxx'.. because knowing HOW/WHERE to get to these sections is -not- something are familiar with. How/Where to find these sections is appreciated.

This is NOT page specific so.. this is globally/site wide. Doesnt matter what page the user 'ends up on'.. if they have NOT seen/accepted the cookie notice.. it should be displayed for them.

I dont know (or if its best practice) to try and add this to the header? or some template? I caution using a template approach as there may be many different templates used through the site? for different sections/areas? and I'd hate to miss an area if going the template route?

How can we do the above?

Thanks!