HTML/CSS - A Responsive Login Form with Bootstrap Online Editor and JavaScript Compiler

html

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
    <link href="https://fonts.googleapis.com/css?family=Montserrat:400,700" rel="stylesheet">
    <link href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet">
    <title>Login</title>
  </head>
  <body>
      <div class="col-lg-6 col-lg-offset-3 col-md-6 col-md-offset-3 col-sm-10 col-sm-offset-1">
      <div class="form">
        <!-- the input -->
      <div class="first-row">
        <a href="#"><img src="https://s13.postimg.org/r7a1xqv1j/1480623034_lock.png" alt="login" class="icon-login"></a>
        <h2 class="first-login">LOGIN</h2>
      </div>
        <form action="#" method="post">
          <div class="input-group">
            <input type="text" class="form-control" placeholder="Username">
            <span class="input-group-addon">
              <span class="fa fa-user fa-2x"></span>
            </span>
          </div>
          <div class="input-group">
            <input type="password" class="form-control" placeholder="password">
            <span class="input-group-addon">

css

/*
    IMPORTANT : 
    Background Image from unsplash 
    
    feel free to use this code ! 
*/
 body{
        padding-top: 50px;
        font-family: Montserrat, sans-serif;
        background-image: url("https://s16.postimg.org/4erognbdx/10px_bg.jpg");
        background-size: cover;
      }
body *{
    transition:0.2 ease;
    -o-transition: 0.2s ease;
    -moz-transition: 0.2s ease;
    -webkit-transition:0.2s ease;
}
      .form{
        padding: 0 0 1em 0;
        width:90%;
        margin: auto;
        text-align: center;
        background: linear-gradient(to bottom, rgba(0,50,150,0.4), rgba(0,0,30,0.3));
        background-size: cover;
        border-radius: 5px;
      }
      .form .first-login{

BROWSER

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