How to add fixed elements on all pages of the site (Wordpress)?

Question

css

It is necessary to make two fixed buttons on all pages of the site.
One on the left, one on the right.
WordPress site, any plugins?
I don't want to edit all theme templates.
Examples of sites where there are such elements:
itvdn.com/ru (social buttons)
www.azbukabloggera.ru (social buttons)
uaweb.ua ("order" - the most appropriate)
top-travel.com.ua (something such)
turbiz.turistua.com (block-right)

Answer 1

In order not to edit all templates, you can add these buttons to the header'a or footer'a template so that the buttons are at the edges in the center of the screen:

position:fixed;
top:50%;
transform: translateY(-50%);
left:0; /* or right:0; */