Reinstate box-selected-background-color
Reinstate box-selected-background-color

Accidentally removed in 55c0bc23488d9cd8dbddfbd4150a019742363e56 (https://github.com/desktop/desktop/commit/55c0bc23488d9cd8dbddfbd4150a019742363e56#diff-1ae30cd070576622a60cbacb5897cad3cf825925b989f2211815aa2b0083fc93L118)

shiftkey/desktop,desktop/desktop,say25/desktop,artivilla/desktop,shiftkey/desktop,say25/desktop,say25/desktop,artivilla/desktop,artivilla/desktop,say25/desktop,desktop/desktop,artivilla/desktop,shiftkey/desktop,desktop/desktop,j-f1/forked-desktop,j-f1/forked-desktop,shiftkey/desktop,desktop/desktop,j-f1/forked-desktop,j-f1/forked-desktop