Android : Android: Custom Background Color for ActionBar

I've read many posts on this problem, but none have helped. Can someone explain why my project will not change the background color of my Action Bar? The docs say to include support library compatibility, via

<item name="background">@drawable/actionbar_background</item>, 

however, I don't know how to specify just a color for the drawable. Putting #57d1a3 here gives an error. I'm not even sure this would solve my problem.

MainActivity:

public class MainActivity extends ActionBarActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}
}

Manifest:

<?xml version="1.0" encoding="utf-8"?>

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/CustomActionBarTheme" >
    <activity
        android:name=".MainActivity"
        android:label="@string/app_name" >
        android:theme="@style/CustomActionBarTheme" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

Main Menu:

<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools" tools:context=".MainActivity">
    <item android:id="@+id/action_settings" android:title="@string/action_settings"
    android:orderInCategory="100" app:showAsAction="never" />
</menu>

And finally, styles.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>
<!-- the theme applied to the application or activity -->
<style name="CustomActionBarTheme"
    parent="@style/Theme.AppCompat.Light">
    <item name="android:actionBarStyle">@style/MyActionBar</item>
</style>

<!-- ActionBar styles -->
<style name="MyActionBar"
    parent="@style/Widget.AppCompat.Light.ActionBar.Solid.Inverse">
    <item name="android:background">#57d1a3</item>
</style>
</resources>