I don’t know why, but I had to manually add those styles in a recent 0.9.6.3 install with AS 1.8.1, otherwise I couldn’t see the highlight on my result pages:
.AS_ajax_highlight1, .ajaxSearch_highlight1 {
background-color: #FFFF00;
color: #000000;
}
.AS_ajax_highlight2, .ajaxSearch_highlight2 {
background-color: #FFFF00;
color: #000000;
}
.AS_ajax_highlight3, .ajaxSearch_highlight3 {
background-color: #FFFF00;
color: #000000;
}
.AS_ajax_highlight4, .ajaxSearch_highlight4 {
background-color: #FFFF00;
color: #000000;
}
.AS_ajax_highlight5, .ajaxSearch_highlight5 {
background-color: #FFFF00;
color: #000000;
}
.AS_ajax_highlight6, .ajaxSearch_highlight6 {
background-color: #FFFF00;
color: #000000;
}
iirc, these styles were added automatically in previous versions (injected into the HTML head, probably via plugin).