[css] How to set div width using ng-style

I am trying to set the div width dynamically using ng-style but it is not applying the style. Here is the code:

<div style="width: 100%;" id="container_fform" ng-controller="custController">
    <div style="width: 250px;overflow: scroll;">
        <div ng-style="myStyle">&nbsp;</div>
    </div>
</div>

Controller:

var MyApp = angular.module('MyApp', []);

var custController = MyApp.controller('custController', function ($scope) {
    $scope.myStyle="width:'900px';background:red";

});

What am I missing?

Fiddle link: Fiddle

ngStyle accepts a map:

$scope.myStyle = {
    "width" : "900px",
    "background" : "red"
};

Fiddle

The syntax of ng-style is not quite that. It accepts a dictionary of keys (attribute names) and values (the value they should take, an empty string unsets them) rather than only a string. I think what you want is this:

<div ng-style="{ 'width' : width, 'background' : bgColor }"></div>

And then in your controller:

$scope.width = '900px';
$scope.bgColor = 'red';

This preserves the separation of template and the controller: the controller holds the semantic values while the template maps them to the correct attribute name.