Dynamic paper-toolbar background in Polymer - polymer

Question

I'm using Polymer 1.0 Starter Kit. I'm trying to change toolbar's background and color when changing routes.
<paper-scroll-header-panel main id="headerPanelMain" condenses keep-condensed-header
header-height="256" condensed-header-height="100">
<paper-toolbar>
<paper-icon-button id="paperToggle" icon="menu" paper-drawer-toggle></paper-icon-button>
<span class="space"></span>
<!-- Toolbar icons -->
<nt-toolbar-icons></nt-toolbar-icons>
<!-- Application name -->
<div class="middle middle-container">
<div class="app-name">[[route.title]]</div>
</div>
<!-- Application sub title -->
<div class="bottom bottom-container">
<div class="bottom-title">[[route.subline]]</div>
</div>
</paper-toolbar>
<div style="height: 1400px;">
<iron-pages attr-for-selected="data-route" selected="{{route.name}}">
<section data-route="home">
{{route.title}} /
</section>
<section data-route="users">
users {{route.params.type}}
</section>
</iron-pages>
</div>
</paper-scroll-header-panel>
</paper-drawer-panel>
Route is defined in elements/routing.html
page('/', function() {
app.route = {
name: 'home',
title: 'noTos+',
subline: ''
}
});
In my shared-styles.html my toolbar is defined this way:
paper-scroll-header-panel#headerPanelMain {
position: absolute;
top: 0;
right: 0;
bottom: 0;
left: 0;
background-color: var(--paper-grey-200, #eee);
/* background for toolbar when it is at its full size */
--paper-scroll-header-panel-full-header: {
background-image: url(../images/headers/bg4.jpg);
}
/* background for toolbar when it is condensed */
--paper-scroll-header-panel-condensed-header: {
background-color: var(--paper-light-blue-600);
}
}
But now I want this color/background-scheme to be changed when the route is changed.
I've tried adding data-route$="[[route.name]]" to paper-scroll-header-panel.
Then I've changed shared-styles.html with the [data-route="home"] selector:
paper-scroll-header-panel#headerPanelMain[data-route="home"] {
--paper-scroll-header-panel-full-header: {
background-image: url(../images/headers/bg3.jpg); //BG CHANGES HERE
}
}
But this doesn't work.
Any other ideas?

Answer 1

Custom styles are only applied at creation time. If you have dynamic changes like you do here, you need to call updateStyles on you custom element or Polymer.updateStyles for a global update. In your case, you would do that when the route changes. You can find more info in the documentation.

Answer 2

you can do the following.
<paper-toolbar id="mainToolbar" class="tall" style$={{computedStyleHandler(color)}}>
computedStyleHandler: function(color){
return 'background-color:' + color + ';'
}