Formatting Issue inside Table

From the Visual Editor in WordPress, when I create a one row, one column table in order to have some content inside a box and with a different background color, the spacing looks good when I edit but after saving the post, all the lines in the table lose spacing and go all the way to the left.

This is how it should be:

events {
             worker_connections  1024;
             use epoll;
             multi_accept on;
            }

This is how it looks after saving:

events {
worker_connections  1024;
use epoll;
multi_accept on;
}

How can I fix this without programming in HTML or CSS?