Div Elements keep disappearing

Hello,

I’ve made a landing website, however everytime I resize the browser the div boxes move too.
So if you see below, the two boxes on the right creates a white space when I make the broswer smaller.

I’ve tried everything and cannot find a solution.

https://miochung7.github.io/Course—Landing-Page/

Because your white box element is fixed size and it doesn’t fit in its original spot that is dynamically adjusted.