Navigation bar moves up with content ionic 3 latest

New to ionic. Downloaded latest blank project and modified to create one input box, a submit button and a navigation bar in the header IOS OS 11 and device 6s. On clicking in the input field and scrolling up ion-content and header moves up. Tried CSS options position: fixed, absolute, ‘iion-fixed’ but none works.

Here is the Ionic info.
cli packages:

@ionic/cli-utils  : 1.12.0
ionic (Ionic CLI) : 3.12.0

global packages:

cordova (Cordova CLI) : 7.0.1 

local packages:

@ionic/app-scripts : 3.0.0
Cordova Platforms  : ios 4.4.0
Ionic Framework    : ionic-angular 3.7.1


ios-deploy : 1.9.1 
ios-sim    : 5.0.13 
Node       : v6.9.4
npm        : 4.2.0 
OS         : macOS Sierra