Fix graphical glitch on dropdown in firefox
Fix graphical glitch on dropdown in firefox

lastorset/rust-playpen,plietar/pony-playpen,plietar/pony-playpen,rust-lang/rust-playpen,chris-morgan/rust-playpen,tilpner/rust-playpen,lastorset/rust-playpen,plietar/pony-playpen,Enamex/rust-playpen,rust-lang/rust-playpen,lastorset/rust-playpen,rust-lang/rust-playpen,Enamex/rust-playpen,lastorset/rust-playpen,tilpner/rust-playpen,tilpner/rust-playpen,chris-morgan/rust-playpen,Enamex/rust-playpen,tilpner/rust-playpen,rust-lang/rust-playpen,Enamex/rust-playpen,plietar/pony-playpen,chris-morgan/rust-playpen,chris-morgan/rust-playpen