Default scope is added instead of required class. Trying to change color in dropdown menu under in using conditional css in Polymer 1.
<paper-item>
<span class$ = {{setClass(item.no)}}> Polymer </span>
</paper-item>
Your example seems ok, just wrap your example double quotes. Beside you may try below:
<span style$ = "color:{{setClass(item.no)}};"> Polymer </span>
setClass(n) {
if(n) return n <100 ? "blue":"red";
}
EDIT
Also, need to remove:<template item-template>
inside oe-combo
.