Just add following code to extra.less template;
CSS:
@media (min-width: (@xf-responsiveMedium + 1))
{
.block {
.message {
.message-inner {
.message-cell--vote {
.message-column,
.contentVote {
position: -webkit-sticky;
position: sticky;
top: @header-navHeight + @xf-messagePaddingSmall;
}
}
}
}
}
}