Color is not changing with this.customStyle - polymer

Question

I can not get the paper tabs selection bar to change color when I invoke changeColor(). Am I doing something wrong?
<dom-module id="paper-tabs-custom">
<style>
paper-tabs {
--paper-tabs-selection-bar-color: white;
}
paper-tab {
--paper-tab-content-unselected: {
opacity: 1.0;
}
}
paper-tab {
font-weight: 700;
}
paper-tab[name="portfolio"] {
width: 161px;
}
</style>
<template>
<paper-tabs noink="true"
attr-for-selected="name"
selected="{{setSelected}}">
<paper-tab data-name="home" data-px="240" name="home" on-tap="jumpToPage">
HOME
</paper-tab>
<paper-tab data-name="portfolio" data-px="180" name="portfolio" on-tap="jumpToPage">
PORTFOLIO
</paper-tabs>
</template>
<script>
Polymer({
is: "paper-tabs-custom",
changeColor: function() {
this.customStyle['--paper-tabs-selection-bar-color'] = 'black';
this.updateStyles();
}
});
</script>
</dom-module>

Answer 1

Yes, you need to set the property on <paper-tabs> directly and call updateStyles directly on it as well. Might be that just calling updateStyles on it directly will do the trick, but I am quite sure that's where the mistake is.
this.$.tabs.customStyle['--paper-tabs-selection-bar-color'] = 'black';
this.$.tabs.updateStyles();