The colours.css file has an RTL rule for a right sided border colour on the poll result bar but this is not needed as the bidi.css file has a rule in it which changes the right sided border to none.

File:

colours.css

Delete:

.rtl .pollbar1, .rtl .pollbar2, .rtl .pollbar3, .rtl .pollbar4, .rtl .pollbar5 {

    border-right-color: transparent;

}