Bagaimana untuk melaksanakan menu terapung sebagai tindak balas

class UserMenu extends React.Component{
 
    constructor(props){
        super(props),
            this.state={
                modalIsOpen:'none',
                atUserItems:false,
            }
 
        this.contentBtn=this.contentBtn.bind(this),
        this.programBtn=this.programBtn.bind(this),
        this.handleMouseOver = this.handleMouseOver.bind(this);
        this.handleMouseOut = this.handleMouseOut.bind(this);
        this.userCenter = this.userCenter.bind(this);
        this.handleMouseUserOver = this.handleMouseUserOver.bind(this);
 
    }
 
    contentBtn(){
        this.context.router.history.push("/details");
    }
 
    programBtn(){
        this.context.router.history.push("/gui");
    }
 
    handleMouseOver(e){
        this.setState({
            modalIsOpen: 'block',
        })
    }
 
    handleMouseOut(){
 
        this.setState({
           modalIsOpen: 'none',
        })
 
    }
    handleMouseUserOver(e){
        this.setState({
            modalIsOpen: 'block',
        })
    }
 
    userCenter(){
        this.setState({
            modalIsOpen: 'none',
        })
    }
 
    render(){
        const {username} = this.props;
        return(
            <div className={styles.body} >
                <div className={styles.uname}
                     onMouseOver={this.handleMouseOver}
                     onMouseLeave={this.handleMouseOut}
                >{username}</div>
 
                <div className={styles.menus}
                     style={{display:this.state.modalIsOpen}}
                     onMouseOver={this.handleMouseUserOver}
                     onMouseLeave={this.handleMouseOut}
                >
                    <ul className={styles.ul}>
                        <li className={styles.li} onClick={this.userCenter}>个人中心</li>
                        <li className={styles.li} >账号设置</li>
                        <li className={styles.li} >注销</li>
                    </ul>
                </div>
            </div>
        )
    }
 
}
 
UserMenu.contextTypes = {
    router: PropTypes.object.isRequired
};
 
export default UserMenu

.body{
    position:relative
}
.menus{
    display:none;
    position:absolute;
    right: 0;
    z-index:999;
}
 
.uname{
    color: white;
    margin-left: 5px;
    margin-right: 10px;
    cursor: pointer;
    padding-top: 25px;
    padding-bottom: 20px;
    padding-left: 5px;
}
.uname:hover{
    color: darkorange;
}
.ul{
    width: 120px;
    background-color: #fff;
    padding: 10px;
    border-radius: 8px;
    -webkit-box-shadow: 0 5px 10px 0 rgba(12,40,46,0.20);
    box-shadow: 0 5px 10px 0 rgba(12,40,46,0.20);
}
.li{
    list-style: none;
    height: 40px;
    display: list-item;
    cursor: pointer;
}
.li:hover{
    color: darkorange;
}