Ionic / Cordova rendering bugs

I'm developing an app with Ionic and Cordova and I'm having some rendering bugs even with the demo app given by ionic. Let's say I have a button and at parts of the button are moved up by one pixel so at the end the border of the button is not straight line. This makes the text very unreadable especially if it's with smaller font size. I can see this bug on the emulator or even when I'm testing the app on my android device. Do you know what can cause this bug and how to fix it?

Thanks :)