To ensure Windowblinds is totally remove, please try purge steps as mention here : [Link]. Reboot after the purge. Retest it.
If the border color still unchange to default. Try this: right click on desktop->Personalization->Themes->Pick any themes that come with Windows->things should change back to Windows default color->retest and report back.
Thank you,
Basj,
Stardock Community Assistant.