2020 updated. I've created this very clean and minimal theme. It fits real good on a 27" iMac. Hope you like it!
Download: https://www.dropbox.com/preview/Aplicaciones/Alfredd/Minimal.alfredappearance?role=personal
Alfredd Site: https://www.alfredapp.com/extras/theme/GFEtQT5IKe/