I'm working on a Lightning App that we want to display properly on mobile, but I'm having trouble with the viewport width when using a mobile device.

Here's my proof-of-problem app:

```
<aura:application extends="force:slds">
    <div style="background: grey">
        foo
    </div>
</aura:application>

```

If I view that on a desktop browser window of width 1200, and check document.documentElement.clientWidth in the javascript console, then I get the result 1200. As expected. Then, resize that window to 375px, and try again: I still get document.documentElement.clientWidth at 375px.

Then, tell Chrome to simulate an iPhone 6. This makes the actual window 375px, but document.documentElement.clientWidth reports 980px.

I found some old discussion of this, saying the problem is the viewport settings and suggesting the use of JS to inject the following header:

```
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0">

```

Obviously, we can't really inject things like that with Locker Service. 

Anything I try to do with responsive layouts on mobile is going to be ineffective if Lightning forces the viewport to be at least 980px. 

Any ideas?