With all due respect, the amount of time with UBB.threads isn't applicable; Isaac has been with the product just as long as I have, just not in an active development role.
He answered your question by pointing to where the information is that you requested, in the change log (which shows the changes in the new release). If you go to post #2 in the changelog discussion (Direct Link
you can clearly see:
New CSS Classes
.shoutintro (Properties for: ShoutChat Box/Page intro text)
This new style class compliments .alt-1 to further customize each of your custom style sheets using the Style Editor. Its not required, but it is available.
Additionally, the changed/new classes were referenced as being in /install/alterstyles-7.6.1.php, which the contents of this file are:
$newstyles['.post-new']['set'] = "background-color:#d30303;
$newstyles['.post.op']['set'] = "background-color:#eee;
$newstyles['.avatar-none']['set'] = "background-color:#eee!important;
$newstyles['#top-button']['set'] = "background:#fff;
height:50px; /* same as width */
width:50px; /* same as height */
border-radius:50px; /* 10px for squared corners */
-webkit-border-radius:50px; /* 10px for squared corners */
-moz-border-radius:50px; /* 10px for squared corners */
bottom:25px /* button location */
right:30px; /* button location */";
$newstyles['#top-button:hover']['set'] = "background-color:#555;";
This isn't a pissing match, and we're here in our own time and on our own dime; everyone can leave their opinions at the door. If you'd like to talk to *official support* and not talk to the developer directly, you're welcome to use the support desk
for paid "official" support.
We are in the process of working on official code, and your question was answered, that you'll need to apply the new/changed CSS from the changelog manually to your styles, I fail to see why anything more needs to be said.
PHP7.3+ is regarded as bleeding edge, any errors found on the newest releases of PHP are being tested, but some things fall by the wayside, especially since most users are just hopping on PHP7. We can't just wave a magic wand and see every error fixed, we have to encounter said error and process code to fix it; and again, most users are NOT running these builds (in fact, the CentOS repo, which most Linux users utilize as a RHEL repo only has PHP72 available).
This thread is closed, and OT posts will be nuked as necessary.