How to style Polymer dropdown menu arrow - css

Question

New to Polymer, and the docs seem a little 'light' on examples. I'm trying to style a dropdown menu so everything is white on a blueish background. Most things (tabs, toast, etc.) are working, but the dropdown-menu stubbornly refuses to show the little 'arrow' button in anything other than murky grey.
Example JSBin
The styling code is:
<style>
:host {
display: block;
/* Main vars */
--ki-teal: #4790A8;
--paper-tabs-selection-bar-color: #fff;
--paper-tab-ink: #fff;
/* Toolbar colours */
paper-toolbar.ki {
--paper-toolbar-background: var(--ki-teal);
}
/* Project select dropmenu colours */
paper-dropdown-menu-light.ki {
--paper-dropdown-menu-color: #fff;
--paper-dropdown-menu-focus-color: #fff;
--paper-dropdown-menu-button: {
color: #fff;
}
--paper-input-container-color: var(--ki-teal);
--paper-input-container-focus-color: #fff;
--paper-dropdown-menu-input: {
border-bottom: none;
};
}
/* Notifications */
#toastSave {
--paper-toast-background-color: var(--ki-teal);
--paper-toast-color: white;
}
}
</style>
But the --paper-dropdown-menu-button doesn't seem to have any effect, or I'm not using it right. Any guidance appreciated.
In addition, you'll see (at least on Chrome/Windows) that the underline bar when the dropdown has focus is not aligned properly with the active tab bar. I guess that's just a Polymer CSS glitch which will get worked out eventually, unless it's something I need to take care of in the <style> section as well?

Answer 1

Use --iron-icon-fill-color in your paper-dropdown-menu class if you want have other iron-icons also which you don't want to style, else you can style use it in host if you want.
Another way of doing it will be giving color to mixin --paper-dropdown-menu-icon. As per paper-dropdown-menu documentation it is
A mixin that is applied to the internal icon
Lastly, if you look at the code of paper-dropdown-menu-light you'll notice that icons have default value as --disabled-text-color. So, if you change this value that should do the trick for you. I'll recommend not to use this method as this is a default variable for material design theme and Polymer has used this as default value at lot of places. So, unless to know what you are doing avoid this method.
In Polymer if an element is using some other element internally you can always refer the style guide of internal element and use it directly. Like here we are using iron-icons styles to style the icon which is inside paper-dropdown-menu
I don't think Polymer has directly mentioned this in their styling guide but you can find this detail written at the end of styling details of paper-dropdown-menu and generalise it
You can also use any of the paper-input-container and paper-menu-button style mixins and custom properties to style the internal input and menu button respectively.