Supporting ie11 and pass style attribute to the element

I am using css variables and I need to support ie11 for my project.
When I try to update css variable in run time with below code it will change the color successfuly in ie11.
```
ShadyCSS.styleSubtree(this, {
'--icon-default-fill-color': 'orange'
});
```

But when I directly pass the style to the component in html it doesn't work.
```

```

By the way I am using Lit Element to create my custom element.