Have you tried to put “!important” after height: 27px? Like this:
#yop-poll-answers-%POLL-ID% ul li {
font-style:normal;
margin:0px 0px 10px 0px;
padding:0px;
font-size:12px;
height: 27px !important;
}
I’ve solved it:D
It seems it has 2 new lines at the end of an included php file.