How to prevent hidden elements to take up empty space?

Hi everyone,

I have hidden tabs on my page that expand when clicked. Problem is that while they are hidden on page load, there is still a huge blank space where they are located, pushing the rest of the content all the way down the page.
Once you click on a tab, the content below does readjust its vertical position, but I want to get rid off this empty space on page load.
Here is the page :
I’ve tried many things but nothing works.

Any tips or advice?

Here is my site Read-Only: LINK
(how to share your site Read-Only link)

aout-us-section and carreers-section maybe needs display non (actually the have display block).