how to fix social media plugin icons

Hi,

For me they already have the same height:
i.imgur.com/GrtTs56.png
Note however that the icons the HikaShop social plugin displays are not static. They are displayed by the social network's javascript dynamically and thus the image itself comes from the social network and cannot be styled much.

If you want images like on your screenshot, then you want static links. You can simply add their HTML in the product / show_default.php view override via the Display>Views menu.
Here is a page which talks about all this:
stackoverflow.com/questions/2954888/how-...a-link-not-an-iframe
And in the answer from "Yevgeniy Afanasyev" there, you can see an example of a static link HTML you can use for yourself.