Angular set style of an html element

https://stackoverflow.com/questions/58414515/typescript-3-7beta-optional-chaining-operator-using-problem

https://stackoverflow.com/questions/50908130/angular-5-add-style-to-specific-element-dynamically

 objectVariableName!.propertyName = 'some value to assign';

    private leftPanel = document.getElementById('left');

    private container = document.getElementById('c');

    @HostListener('document:mousemove', ['$event'])

    onMouseMove(e: MouseEvent) {

        var offsetR= this.container!.clientWidth - (e.clientX - this.container!.offsetLeft);

        this.leftPanel!.style.right = offsetR+ 'px';