Untitled

<!DOCTYPE html>
<html>
<head>
  <title>noname</title>
  <!--<link rel="stylesheet" type="text/css"href="C:firstpublicnoname.css">-->
  <style type="text/css">
    input{
        resize: none;
        border-radius: 5px;
        size: 50px;
        height: 100%;
    }

    #main{
        text-align: center;
        padding: 20px;
        border: 5px solid;
        width: 50%;
        background-color: #c2e5ef;
        background-clip: border-box;

    }

    .button{
        color: #fff;
        background-color: #3fb2bf;
        margin: 10px 2px;
        border: none;
        font-size: 20px;
        width: 100px;
        height: 50px;
        border-radius: 15px
    }

    #login-div{
        text-align: center;
    }

    #logout-div{
        text-align: center;
    }
  </style>
</head>
<body>
 <div id="main">
   <div id="login-div">
     <label><b style="font-size: 20px;">Username:<input type="text" name="username" id="username" placeholder="Enter Username"><br>
     </label>
     <br>

     <label>Password:<input type="text" name="password" id="password" placeholder="Enter Password"></label><br>

     <input type="button" name="login" value="Login" class="button" onclick="login()">
     </div>

     <div id="logout-div">
     <p>you are logged in</p>
     <input type="button" name="logout" value="Logout" class="button"  onclick="logout()">
    </div>

    <script src="https://www.gstatic.com/firebasejs/4.9.0/firebase.js"></script>

    <script type="text/javascript">
        var config = {
            apiKey: "AIzaSyDf4ndBB-CXJwaYVLXXQacFmX3O9eZbUZk",
            authDomain: "first-b14b2.firebaseapp.com",
            databaseURL: "https://first-b14b2.firebaseio.com",
            projectId: "first-b14b2",
            storageBucket: "first-b14b2.appspot.com",
            messagingSenderId: "103220354303"
        };
        firebase.initializeApp(config);

        firebase.auth().onAuthStateChanged(function(user) {
          if (user) {
            // User is signed in.
            document.getElementById("login-div").style.display="none";
            document.getElementById("logout-div").style.display="block";
          } else {
            // No user is signed in.
            document.getElementById("login-div").style.display="block";
            document.getElementById("logout-div").style.display="none";
          }
        });

        function login(){
            var email=document.getElementById("username").value;
            var pass=document.getElementById("password").value;

            firebase.auth().signInWithEmailAndPassword(email, pass).catch(function(error) {
                // Handle Errors here.
                var errorCode = error.code;
                var errorMessage = error.message;

                window.alert("error");
                // ...
            });
        }

        function logout(){
            firebase.auth().signOut().then(function() {
                // Sign-out successful.
            }).catch(function(error) {
                // An error happened.
            });
        }
     </script>
  </div>
 </body>
</html>

input{
    resize: none;
    border-radius: 5px;
    size: 50px;
    height: 100%;
}

#main{
    text-align: center;
    padding: 20px;
    border: 5px solid;
    width: 50%;
    background-color: #c2e5ef;
    background-clip: border-box;

}

.button{
    color: #fff;
    background-color: #3fb2bf;
    margin: 10px 2px;
    border: none;
    font-size: 20px;
    width: 100px;
    height: 50px;
    border-radius: 15px
}

#login-div{
    text-align: center;
}

#logout-div{
    text-align: center;
}

var config = {
    apiKey: "AIzaSyDf4ndBB-CXJwaYVLXXQacFmX3O9eZbUZk",
    authDomain: "first-b14b2.firebaseapp.com",
    databaseURL: "https://first-b14b2.firebaseio.com",
    projectId: "first-b14b2",
    storageBucket: "first-b14b2.appspot.com",
    messagingSenderId: "103220354303"
};
firebase.initializeApp(config);

firebase.auth().onAuthStateChanged(function(user) {
  if (user) {
    // User is signed in.
    document.getElementById("login-div").style.display="none";
    document.getElementById("logout-div").style.display="block";
  } else {
    // No user is signed in.
    document.getElementById("login-div").style.display="block";
    document.getElementById("logout-div").style.display="none";
  }
});

function login(){
    var email=document.getElementById("username").value;
    var pass=document.getElementById("password").value;

    firebase.auth().signInWithEmailAndPassword(email, pass).catch(function(error) {
        // Handle Errors here.
        var errorCode = error.code;
        var errorMessage = error.message;

        window.alert("error");
        // ...
    });
}

function logout(){
    firebase.auth().signOut().then(function() {
        // Sign-out successful.
    }).catch(function(error) {
        // An error happened.
    });
}

<!DOCTYPE html>
<html>
<head>
  <title>noname</title>
  <link rel="stylesheet" type="text/css"href="style.css">
</head>
<body>
 <div id="main">
   <div id="login-div">
     <label><b style="font-size: 20px;">Username:<input type="text" name="username" id="username" placeholder="Enter Username"><br>
     </label>
     <br>

     <label>Password:<input type="text" name="password" id="password" placeholder="Enter Password"></label><br>

     <input type="button" name="login" value="Login" class="button" onclick="login()">
     </div>

     <div id="logout-div">
     <p>you are logged in</p>
     <input type="button" name="logout" value="Logout" class="button"  onclick="logout()">
    </div>

    <script src="https://www.gstatic.com/firebasejs/4.9.0/firebase.js"></script>

    <script src="main.js"></script>
  </div>
 </body>
</html>