$tabs-ios-tab-font-size doesn't change font-size

I’m trying to change my tab names font-size of a component, but it doesn’t work.

To do this, I edit the src/theme/variables.scss. like it teach here http://ionicframework.com/docs/v2/theming/overriding-ionic-variables/, using the $tabs-ios-tab-font-size:variable.

My code look like this:

// Shared Variables
// --------------------------------------------------
// To customize the look and feel of this app, you can override
// the Sass variables found in Ionic's source scss files.
// To view all the possible Ionic variables, see:
// http://ionicframework.com/docs/v2/theming/overriding-ionic-variables/

$text-color:        #000;
$background-color:  #fff;

$tabs-ios-tab-font-size: 6px;

but the result is:


How can I do to change the tab name font size?

md and wp is correct but ios is not working.