导航栏没有边框

Question

我的代码如下：

   render() {                                                           
     return (                                                           
       <React.Fragment>                                                 
         <Navbar collapseOnSelect fixed="top">                          
           <Navbar.Brand href="/home/">
             <img src={logo} alt="Picture" height="20px" />               
             <span style={{ color: 'grey' }}>Site management</span>   
           </Navbar.Brand>
           <Navbar.Collapse>                                            
             <Nav variant="pills" defaultActiveKey="/home/">              
               <Nav.Item>          
                 <Nav.Link eventkey={1} href="/home/">                    
                   Home
                 </Nav.Link>
               </Nav.Item>
               <Nav.Item>
                 <Nav.Link eventkey={2} href="/home/about">              
                   About
                 </Nav.Link>                                            
               </Nav.Item>
             </Nav>
             <Nav className="justify-content-end">                      
               <CurrentUser/>
             </Nav>
           </Navbar.Collapse>                                           

这不起作用...没有寄宿生，导航栏没有对齐顶部，有什么建议吗？