Merging a dynamic style with a predefined style in a React app

styleMerge.js

class InfoPanel extends React.Component {

//   a pre-defined style
  scrollBarStyle = {
      top: 0,
      position: 'absolute',
      width: '18px',
      height: 54,
      background: '#434344'
    }

  .... code excluded for clarity....

  render() {
    return (
      <div className="scrollBarHolder" style={this.scrollBarHolderStyle}>
        {/* NOTE TO SELF: I needed to merge the existing style with one updated property ... set my Motion in this case */}
        <div className="scrollBar" style={ Object.assign( {}, this.scrollBarStyle, {transform: `translateY(${this.state.scrollBarOffset}px)`} )}></div>
      </div>
    )
  }
}