Two columns: one fixed when the content ends, another one do scroll.

[natvalmun]

Hello,

 

I would like to do that my posts have two columns, in one I will put the text and in the other column, I will put a images gallery. But the problem is when a I want the text to be fixed when ends, while the other column do scroll until the images ends. In this way, when the user is seeing the pictures, in the other column will be the text and no a empty space.

 

You can see some examples in this url:

https://readcereal.com/malta/

https://readcereal.com/antarctica/

 

How would this be done in CSS? What would be the code?

 

Thank you so much and sorry for my english. I hope you have explained me well.