ember-basic-dropdown-wormhole hidden behind

tl;dr the following css property fixes my issue:
```css
#ember-basic-dropdown-wormhole {
z-index: 100;
position: relative;
}
```
but it feels wrong/hacky..? The value `100` is the smallest that resolved the issue.

---

I'm attempting to use `paper-select`:
```hbs
{{#paper-select
disabled=disableModelSelect
label="Model"
options=deviceModels
selected=selectedModel
onChange=(action 'foo') as |thing|}}
{{thing.abbrev}}
{{/paper-select}}
```

However, nothing is appearing on my screen. After trial/error I found that I could partially reveal the menu by removing this css rule from my application:
```css
body > [class="ember-view"] {
height: 100%;
}
```

Here's a quick demo of what that alone yields:

You'll notice a chunk is clipped -- that's where `body > [class="ember-view"]` ends and the menu is revealed. But the part that is missing is being clipped because the root ember-view is on top of it. With the css adjustment mentioned at be ginning of this issue I correctly see the following: