blank site after inputing code in style.php

Help!! This is the second time this has happened! I tried changing the code in the style.php section of the editor with the following:

.archive-title {
font-size: 20px;
margin-bottom: -3px;
visibility: hidden;
}

As a result, I lost my site and it’s completely blank. I hit the back button and deleted the code but it didn’t help. How do I restore If I can’t see anything in my dashborad? I did this before in the past and had to re-install the theme and lost all of my changes.