How to stretch a block to the entire available width between two floated blocks with a known width?

Question

css

Good afternoon,
I have a problem, the destruction of which I can not find on the Internet.
There are 3 blocks:
The left and right blocks have a fixed width, the center class must stretch to full width.

Answer 1

If the left and right have a fixed width, then make the central block margin-left and margin-right by this value and set width: 100%

Answer 2

https://codepen.io/Nickolyashka/pen/EvMyJJ

Answer 3

the parser ate something from you after "there are 3 blocks".
but the search was bad - overflow:hidden gets between floats well, but this solution depends on the order of the blocks https://jsfiddle.net/9L0abuw8/