$background-ios-color works, $background-md-color doesn't

I’m trying to use ezAR and I need to make the background of my home page transparent. Using Sass variables, I can set the ios background color transparent, but not the md background.

variables.scss

$text-color:                    #666;
$background-color:              #fff;
$font-size-root:                100%;
$tabs-ios-tab-font-size:        20px;
$tabs-ios-tab-icon-size:        45px;
$card-ios-title-text-color:     #192857;
$card-md-title-text-color:      #192857;
$card-md-text-color:            #666;
$toolbar-ios-title-text-color:  #192857;
$toolbar-md-title-text-color:   #192857;
$list-ios-title-text-color:     #192857;
$list-md-title-text-color:      #192857;
// This line is working
$background-ios-color:         transparent;
// This line isn't working
$background-md-color:          transparent;

I tried inline CSS as a workaround, but it isn’t working either

home.html

<ion-content style="background-color: transparent;">

I’m testing using Chrome/Chrome Canary inspector and Ionic View. All three show the same thing. IPhone on the left, Android on the right.

Ionic info:
Cordova CLI: 6.4.0
Ionic Framework Version: 2.0.0-rc.3
Ionic CLI Version: 2.1.13
Ionic App Lib Version: 2.1.7
Ionic App Scripts Version: 0.0.45
ios-deploy version: 1.9.0
ios-sim version: 5.0.11
OS: OS X El Capitan
Node Version: v6.9.1
Xcode version: Xcode 8.1 Build version 8B62