How do I hide navbar when i select login or signup in react?

I am trying to hide the navbar when I select a log in my app. I am working with react hooks and I have no idea how to do it.

My main looks like this :

<div>
        <Menu/>
        <Router>
            {
                domainList === "error" ?
                    (
                        <ErrorMessage
                            message="Error"
                        />
                    )
                    :
                    Boolean(domainList) === true ?
                        (
                            <Main
                                endpoint={endpoint}
                                callbackReFetchDomains={reFetchDomains}
                                domainList={domainList}
                                hasDomainListError={hasDomainListError}
                                appendDomainList={appendDomainList}
                                changeDomainList={changeDomainList}
                            />
                        )
                        :
                        (
                            <LoadingSpinner/>
                        )
            }
        </Router>
    </div>

My main looks like this :

<>
        <div>
            {/*Switch will only render the first matched <Route/> child.*/}
            <Menu/>
            <Switch>
                <Route path="/topics">
                    <ExampleComponentStructure/>
                </Route>
                <Route path="/login">
                    <Login/>
                </Route>
                <Route path="/domains">
                    <DomainList
                        endpoint={props.endpoint}
                        callbackReFetchDomains={props.callbackReFetchDomains}
                        domainList={props.domainList}
                        hasDomainListError={props.hasDomainListError}
                        appendDomainList={props.appendDomainList}
                        changeDomainList={props.changeDomainList}
                    />
                </Route>
                <Route path="/signup">
                    <Signup/>
                </Route>
                <Route path="/users">
                    <UserMaintainList
                        endpoint={props.endpoint}
                    />
                </Route>
                <Route path="/">
                    <StickerList
                        endpoint={props.endpoint}
                        callbackReFetchDomains={props.callbackReFetchDomains}
                        domainList={props.domainList}
                        hasDomainListError={props.hasDomainListError}
                        changeDomainList={props.changeDomainList}
                    />
                </Route>

            </Switch>
        </div>
    </>

I know that the code is not clean. I am just starting with react and need some help doing this login screen. Thank you.