Inline style of Office Fabric UI library in spfx webpart

After upgraded the @microsoft/sp-office-ui-fabric-core library, all inline styles gone, to get it back, you just need to do:
import '@microsoft/sp-office-ui-fabric-core/lib/office-ui-fabric-core-sass/FabricCore.css';
Here is the test case:
public render(): React.ReactElement<IShortCutProps> { return ( <div className={styles.shortCut}> <div className={styles.container}> <div className={styles.row}> {this.menus} </div> </div> <div className="ms-Grid" dir="ltr"> <div className="ms-Grid-row"> <div style={{ backgroundColor: 'red' }} className="ms-Grid-col ms-sm6 ms-md4 ms-lg2">A</div> <div style={{ backgroundColor: 'yellow' }} className="ms-Grid-col ms-sm6 ms-md8 ms-lg10">B</div> </div> </div> </div> ); }
