Question: I have a .txt textfile with a list formatted like 
`[' ok ', ' test ', ' help ']`
How can I read/import this textfile list into a python list?

Answer: 
If you want to customize the css of the tooltip, then you can use `::ng-deep`. Add the following styles in your component's styles:

```css
::ng-deep .mat-tooltip {
    /* your own custom styles here */ 
    /* e.g. */
    color: yellow;
}

```

Another option is to set the [View Encapsulation](https://angular.io/guide/component-styles#view-encapsulation) to None in your component:

```js
@Component({ 
    templateUrl: './my.component.html', 
    styleUrls: ['./my.component.css'], 
    encapsulation: ViewEncapsulation.None
})

```

Then in your component css you dont have to use `::ng-deep`.

```css
.mat-tooltip {
    /* your own custom styles here */ 
    /* e.g. */
    color: yellow;
}

```
Late at the party :-| Just in case somebody has as well the troubles. Angular Material won't apply the class if its encapsulated. The solution?

Put the style in the `styles.scss` file and using `!important`. This finally solved my problem. e.g.

```
.red-tooltip {
    background-color: red !important;
    font-size: larger !important;
}

```