Hi there!
Thanks for reaching out to us.
Did you mean the bottom shadow of the button after hover? If you want to change only for the indicated button, you may try it in your custom CSS:
#btn-1526364078954.sppb-btn-default:hover:after, #btn-1526364078954.sppb-btn-default:focus:after {
background-image: linear-gradient(-131deg, #00ff76 0%, #00DBFF 100%);
}
If you mean all the default button hover shadow effect color then you can use the following code:
.sppb-btn-default:hover:after, .sppb-btn-default:focus:after {
background-image: linear-gradient(-131deg, #00ff76 0%, #00DBFF 100%) !important;
}
You can use any of your desired color in the above code snippets.
Note: Path towards custom CSS(Joomla 4): System>Site Templates Styles> Click on your current default template name then choose Template Options. Then find custom CSS within the custom code.
https://prnt.sc/5mBuSRh907N3
https://prnt.sc/ooiq-lkMEXr_
https://prnt.sc/nunlX-f5AhK1
Best Regards