creating amending email invitation in library

We have an email invitation created in the library. This was created using Javascripts code by Qualtrics team when we first onboarded them. We would like to make some changes to the look and feel, particularly to width of the text and spacing between the lines, but I am not familiar with. I believe there are some elements in the code that adjust the invites depending on the device and screen size. This is something I am conscious of breaking. Does anyone here know what is my best option to amend this, as apparently the support team does not deal with this.