Bootstrap - change form group's css #media size - css

Question

I know I am doing this wrong but I have no idea how to fix it properly.
I have a sign up form that has a display: relative, on col-lg. But I did not know how to change a css based on a screen size. So I just duplicated the sign up form and gave it a different class name and changed the css accordingly.
Problem I came across was that if someone types information and then decides to adjust screen, all of there info disappears(because it is on the col-lg!)
How can I fix this issue without having to duplicate the form? I would like to not use jquery or javascript, but if I have to I will.
.form-signup {
position: absolute;
bottom: 70px;
right: 0;
margin-right: 35px; }
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.4/jquery.min.js"></script>
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.4/css/bootstrap.min.css" rel="stylesheet">
<!-- First form -->
<div class="col-xs-4 col-sm-4 col-md-4 pull-right form-signup hidden-md hidden-sm hidden-xs">
<form role="form">
<h2>
<div class="text-center lead p-color">Tagline</div>
</h2>
<div class="row">
<div class="col-xs-12 col-sm-6 col-md-6">
<div class="form-group">
<input type="text" name="first_name" id="FN" class="form-control input-md" placeholder="First Name" tabindex=1 autofocus>
</div>
</div>
<div class="col-xs-12 col-sm-6 col-md-6">
<div class="form-group">
<input type="text" name="last_name" id="LN" class="form-control input-md" placeholder="Last Name" tabindex=2>
</div>
</div>
</div>
<div class="form-group">
<input type="email" name="email" id="EM" class="form-control input-md" placeholder="Email Address" tabindex=3>
</div>
<div class="form-group">
<div class="form-group">
<input type="password" name="password" id="PW" class="form-control input-md" placeholder="Password" tabindex=4>
</div>
</div>
<div class="checkbox">
<label>
<input class="checkbox-focus" type="checkbox" tabindex=5>I agree to
<a class="ri-anchor" href="#" tabindex=6>terms</a>
</label>
</div>
<div class="row">
<div class="form-group register-div">
<input type="submit" value="Sign Up" class="btn btn-primary btn-block btn-lg" tabindex=7>
</div>
</div>
</form>
</div>
<!-- Second Form -->
<div class="row row-offset center-block">
<div class="col-md-12 text-center hidden-lg"><img src="images/landing-md-xs.png" class="img-responsive center-block" alt=" animation" style="height: auto; width: 500px;"/></div>
<div class="col-xs-offset-2 col-xs-8 col-md-offset-3 col-md-6 hidden-lg">
<form role="form">
<h2>
<div class="text-center lead p-color">TAGLINE</div>
</h2>
<div class="row">
<div class="col-xs-12 col-sm-6 col-md-6">
<div class="form-group">
<input type="text" name="first_name" id="first_name" class="form-control input-md" placeholder="First Name" tabindex=1 autofocus>
</div>
</div>
<div class="col-xs-12 col-sm-6 col-md-6">
<div class="form-group">
<input type="text" name="last_name" id="last_name" class="form-control input-md" placeholder="Last Name" tabindex=2>
</div>
</div>
</div>
<div class="form-group">
<input type="email" name="email" id="email" class="form-control input-md" placeholder="Email Address" tabindex=3>
</div>
<div class="form-group">
<div class="form-group">
<input type="password" name="password" id="password" class="form-control input-md" placeholder="Password" tabindex=4>
</div>
</div>
<div class="checkbox">
<label>
<input class="checkbox-focus" type="checkbox" tabindex=5>I agree to
<a class="ri-anchor" href="#" tabindex=6> terms</a>
</label>
</div>
<div class="row">
<div class="form-group register-div">
<input type="submit" value="Sign Up" class="btn btn-primary btn-block btn-lg" tabindex=7>
</div>
</div>
</form>
</div>
</div>

Answer 1

col-lg-x is a bootstrap class that assigns your div grid size with the value of x. it's for large screen. but removing shouldn't drastically change the design like you have presented above. It's because you have mis-linked bootstrap css file. Also on the code above you have included jquery instead of bootstrap.
Edit : for Problem I came across was that if someone types information and then decides to adjust screen, all of there info disappears(because it is on the col-lg!)
For this add other classes col-md-x, col-xs-x` on the div as according to your need of x value.