Fix x-axis position.
Fix x-axis position.

This gest the centring calculation correct.

Also, remove the shadow; it's not visible.

willsALMANJ/vimium,poacher2k/vimium,gdh1995/vimium,poacher2k/vimium,mrmr1993/vimium,willsALMANJ/vimium,smblott-github/vimium,poacher2k/vimium,gdh1995/vimium,philc/vimium,philc/vimium,decaffeinate-examples/vimium,smblott-github/vimium,philc/vimium,decaffeinate-examples/vimium,mrmr1993/vimium,decaffeinate-examples/vimium,mrmr1993/vimium,gdh1995/vimium,willsALMANJ/vimium,smblott-github/vimium