fix(styles): Add style overrides to fabric default styles

src/components/UserPicker/UserPicker.css

@@ -0,0 +1,10 @@
+/*! Copyright (c) Microsoft Corporation. All rights reserved. Licensed under the MIT license. */
+@import 'src/css/variables/colors.css';
+
+.y-userpicker-suggestions__container .ms-TooltipHost {
+  color: $textColor;
+}
+
+.y-userpicker-suggestions__container .ms-PickerItem-removeButton__color-primary {
+  color: $textColor;
+}

src/components/UserPicker/UserPicker.tsx

@@ -14,6 +14,13 @@ export { IPersona, IBasePickerProps, IBasePickerSuggestionsProps };
 export default class UserPicker extends React.Component<IBasePickerProps<IPersona>> {
   public render() {
     const { onResolveSuggestions } = this.props;
-    return <NormalPeoplePicker onResolveSuggestions={onResolveSuggestions} />;
+    const suggestionsClass: IBasePickerSuggestionsProps = { className: 'y-userpicker-suggestions__container' };
+    return (
+      <NormalPeoplePicker
+        className="y-userpicker__container"
+        pickerSuggestionsProps={suggestionsClass}
+        onResolveSuggestions={onResolveSuggestions}
+      />
+    );
   }
 }