Hi

Thanks for contacting us. Use this CSS in your custom.css file

#sppb-addon-tU1ZVfV6iEx_88KBMlpzk #btn-tU1ZVfV6iEx_88KBMlpzk.sppb-btn-custom{
    border: 1px solid #fff;
}

-Regards.

How to make for everyone

sppb-btn-custom

or

https://prnt.sc/7IoOEVd7z1S2

I would like to have all custom buttons

https://prnt.sc/YAyi8oWDT-mJ

Use this custom CSS in your custom.css file

#sppb-addon-1688720211543 #btn-1688720211543.sppb-btn-primary{
  border: 2px solid #cb1d1d;
}
#sppb-addon-tU1ZVfV6iEx_88KBMlpzk #btn-tU1ZVfV6iEx_88KBMlpzk.sppb-btn-custom{
    border: 1px solid #fff;
}
#sppb-addon-W0PL-BB6HkXAwtpsILXA_ .sppb-form-builder-btn button{
   border: 1px solid #cb1d1d;
}