I've been in this industry for over 10 years. I have to say I've never seen anything such a mess as this new Jupiter theme. I CANNOT work with it. It needs to go.
There's no logical reason why cPanel wouldn't allow us to customise WHM themes. In fact they don't even need to do that. They don't even need to change anything at all. They have a perfectly working "classic" WHM style version that was fully aligned and fully up to date. The new "Jupiter" theme was created to be IN ALIGNMENT with the current version of cPanel, just to replace the classic one. So frankly, the argument that it's extra work to keep two themes up to date is complete nonsense. There's no extra work at all because as you say, you're just tweaking very small things as you go along.
If you really want to introduce the Jupiter theme, which I've looked on a lot of places and not just here, I haven't found one positive comment about it yet - but if you really want to introduce the Jupiter theme, then at least provide it alongside the classic WHM theme and edit it at the same time so people actually have a choice. You cannot take away people's choice like this it is simply not ethical.
What cPanel are doing here is effectively what we're seeing happen all across the web with many tech companies as well. Just like Microsoft do, just like all these clunky new UI interfaces cropping up right over the web. You realise you have a monopoly on this market, and you're effectively changing your products to make it easier for people who haven't got a clue what they're doing and do not understand server management, effectively "rookies", to try and make it easier for them to manage a server. This is not possible. It doesn't work. You cannot and should not take shortcuts in this field.
Not only is it not possible to achieve this, but it's also actually very dangerous, because this is why you get so many "developers" who go on some 6 week course and then suddenly believe they're a coder. You're targeting people who have no experience in this field and trying to make it easier for them to get into this, but these people do not and never will understand things to the level that is needed to manage a server. They're probably not even interested. You're targeting completely the wrong market. It's irresponsible. This is precisely the reason why so many websites get hacked, because they were built by junior developers who do not properly understand how to effectively secure a system.
I see first hand the effects of this on a daily basis and just how badly developed some of these systems are. Developers like me and probably many others who have commented are left cleaning up the mess. This is not the way forward, it's the way back.
WHM is a server management tool - it's not supposed to be aimed at rookies. It's for experienced professionals who know what they are doing. But what you're actually doing is trying to target the rookies and encourage them to get into something that's way out of their depth by making it look "easy", and alienating your actual core base which are the people who actually use this product.
This is why I create everything myself, because you cannot rely on other people to do things properly. And to be fair I'm now considering whether I should do the same for server management software, whenever I have the time. Because I can clearly see that from this thread this is going the same way. So for that reason, I'm struggling.
I cannot and will not use a product that does not function properly. If the ability to use the original style is not restored, I will have no choice but to look for and use an alternative product.
I have noticed by the way you deleted my thread asking about whether the style can be reverted. This is pretty appaling really, considering I was only asking a simple question.