How do you style a custom element's tag from within the element?

How do you style a custom element's tag from within the element?

I'm trying to style a custom element tag, and can't seem to do it from
within the element's <style> tag, or at least I don't know what selector
to use. I've tried the custom element's tag name and template, but neither
work.
<polymer-element name="my-test" constructor="MyTest">
<template>
<style>
my-test {
border: solid 1px #888; /* doesn't work */
}
.title {
color: blue; /* works */
}
</style>
<div class="title">{{ title }}</div>
</template>
I'm using polymer.dart, so there may be some lag in its implementation,
but I'd like to know how it should work in polymer.js.