Background-position incompatible for animation

Ionic Framework
1

Its declared on

how to work with animations.

But when using
‘background-position’
the compiler throws syntax error. I think in case of the “-” in the CSS keyword.

Any suggestion?

const animation: Animation = this.animationCtrl.create()

    .addElement(document.querySelector('.hero'))

    .duration(1000)

    .iterations(Infinity)

    .easing("linear")

    .keyframes([

      { offset: 0, background-position:'0 0', opacity: '0', transform: 'scale(0)' },

      { offset: 1, background-position:'-170px 0', opacity: '0.99', transform: 'scale(1)' }

    ])

    .fromTo('opacity', '1', '0.5');

    animation.play();