How to implement switching css files?

Question

PHP

Example:
raresolution.com/themeforest/zero/html/index.html#about (gear on the left)
Maybe there is a jquery plugin, googled nothing working.

Answer 1

You either chose the wrong language, or you need to master the ajax technology.
And in general, if you need to send somewhere, for example, a form, as I understand it, to a payment system, then why set anything to the $Subtotal_P variable at all, you just send the form and that's it, otherwise where you send it will process the data and that's it.
I understand you connect the payment system, right?

Answer 2

And why do you need Google if you have a ready-made site for what you want and how you want, it’s not easier to open the site’s code and THERE look at how the implementation was created, moreover, changes can be made as you like in ONE css file without changing the entire structure. On pure JS, you can write this without plugins, it’s enough to apply an event onclick to the button, and then change the properties of the elements themselves through CSS

Answer 3

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