Pure CSS Login Form

<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Pure CSS Login Form</title>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width" />
    <link rel="stylesheet" href="styles.css" />
  </head>
  <body>
    <div class="container">
      <div class="center">
        <h1>Login</h1>
        <form action="" method="POST">
          <div class="txt_field">
            <input type="text" name="text" required />
            <span></span>
            <label>Username</label>
          </div>
          <div class="txt_field">
            <input type="password" name="password" required />
            <span></span>
            <label>Password</label>
          </div>
          <div class="pass">Forget Password?</div>
          <input name="submit" type="button" value="Submit" />
          <div class="signup_link">
            Not a member?<a href="signup.php">Signup</a>
          </div>
        </form>
      </div>
    </div>
  </body>
</html>