Hi!

Regarding performance and improvement of the website's speed. What can I do with

https://fonts.googleapis.com/css2?family=Lora:wght@700&family=Poppins:wght@300;400;500;600&display=swap

https:///oc-content/themes/delta/css/style.css?v=20211115170357

https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.12.1/css/all.min.css

https:///oc-includes/osclass/assets/js/jquery3/jquery.min.js

https:///oc-includes/osclass/assets/js/jquery3/jquery-ui/jquery-ui.min.js

in order to eliminate render-blocking resources?

@sess01
Based on my experience, if you eliminate render blocking resources, then new problem arrive with "changing content" - because if you move fonts to the end/footer, site will start loading with some initial font, but then font is switched to final one - that is also issue.
Same with styles, site design will change as site loads, so it require another styles to be loaded at start those will keep content in consistent way... never ending loop...

it's like a vicious circle...

VSC found mistakes in style.css.

1) 5 mistakes with -webkit-backface-visibility: hidden; Also define the standard property 'backface-visibility' for compatibilitycss(vendorPrefix) hidden;

How can I fix it?

2) Can I just delete exclamation marks here?
!#home-cat2 a:first-child {margin-left:0;}.     
    !#home-cat2 a:last-child {margin-right:0;}
    !#home-cat2 .box {float:left;clear:both;width:100%;position:relative;text-align:

3) 5 mistakes with float:left;display:inline-blockinline-block is ignored due to the float. If 'float' has a value other than 'none', the box is floated and 'display' is treated as 'block'css(propertyIgnoredDueToDisplay

Can I just delete float:left or can I replace text-align instead of float:left?

@sess01
1) https://www.w3schools.com/cssref/css3_pr_backface-visibility.asp
2) ! is commenting line, you can remove commented lines
3) you can replace inline-block with block

 1) according to https://www.w3schools.com/cssref/css3_pr_backface-visibility.asp

Should I just add?:   -webkit-backface-visibility: hidden; backface-visibility: hidden;
2) input[type="text"] {}Do not use empty rulesetscss(emptyRules)

Can I just delete it?

3) https:///oc-includes/osclass/assets/js/jquery3/jquery.min.js

https:///oc-includes/osclass/assets/js/jquery3/jquery-ui/jquery-ui.min.js
Can I modify something with these lines? They related to when I enable Minify/optimize merged JS scripts?

1) I would say it is irrelevant nowadays.
2) you can remove
3) on your own risk

1) I would say it is irrelevant nowadays.

I don't understand

How can I fix this error? -webkit-backface-visibility: hidden;

@sess01
It's not error, I do not see any issue there. If you want to fix css notifications, use forums of that validation service.
Anyway it is losing of your valuable time, being compliant with random validator has no effect on website at all.