Hello,

1. Because your custom CSS works globally due to selectors. If you want to apply such styles to a specific element, you need to use the “CSS Classes” field in the settings of the section: https://prnt.sc/QpEiI1qSGwcL

So you can define there any CSS class like “custom-title” and then your selector will be like .custom-title h4, as a result, that custom will work only for the titles that are in that specific section (https://prnt.sc/nZ5btOaeVWBr) that has custom-title CSS class defined in its settings.

2. As for the search, on my side the search by title and SKU works well, here are a few videos:

https://gyazo.com/22d22284e3af0d6ca3985fb89c2fe9bd

https://gyazo.com/0147a1cb844bf9c6f89e4e5b52ff5dc9

The Relevanssi search was enabled while testing: https://prnt.sc/sRK1ZgZ19hG8

Kind Regards