Why can't I set the size of the svg icon?

Question

css

I have 2 icons.
The first is instagram, this icon is displayed as it should be (the icon itself is 25*25, together with the background - 49*49)
The second icon is facebook. The icon itself should be - 11*20 (actually - 5*11 ), BUT, together with the background, the icon takes the desired size - 39*38.

Why is there such a difference in the behavior of these two icons? And why can't I get the right size for facebook?

Answer 1

Examine vector sprites.
And in your last question about these icons, I wrote how they are made.
https://jsfiddle.net/ytuba2ce/
If you need different sizes, set additional classes.