How to move a block down?

Question

css

I made the header of the site fixed, after which the bottom block went up.
How to lower it down if there is no exact height of the cap? (the specific height is not specified, the height is set by padding)

Answer 1

Something like this
https://jsfiddle.net/kwo8emox/9/
In continuation of twobomb 's answer

Answer 2

you can get the height through js on the header class, and indent + header height. even with padding you can measure the height. set the minimum height.