Bootstrap 3 inline-form with different widths for input boxes - css

Question

I have some bootstrap 3.0 based markup that produces an inline form like this:
The code for this is:
<div class="container">
<form class="form-inline" role="form" id="gh_save">
<div class="form-group">
<input type="text" placeholder="Github username" class="form-control" id="gh_user">
</div>
<div class="form-group">
<div class="col-lg-6">
<input type="text" placeholder="API Key" class="form-control" id="gh_apikey">
</div>
</div>
<button type="submit" class="btn btn-success"> Save </button>
</form>
I am trying to increase the width of the second box (API Key) to be twice what it is now, but no matter what I change the width of the div holding the second input is changing the width. Can someone show me how this done?
when I manually set the width of the second INPUT, I get this:

Answer 1

<form class="form-horizontal">
<div class="form-group">
<div class="col-xs-4">
<input type="text" placeholder="Github username" class="form-control" id="gh_user"/>
</div>
<div class="col-xs-6">
<input type="text" placeholder="API Key" class="form-control" id="gh_apikey" />
</div>
<div class="col-xs-2">
<button type="submit" class="btn btn-success"> Save </button>
</div>
</div>
</form>
DEMO
PS : close input tags as <input class="" />
Final edit here, I guess external bootstrap 3.1.1 was not getting included thus you got the result in 3 different lines, take a look at this
Final Demo
<link rel="stylesheet" type="text/css" href="http://netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap.min.css">
<div class="container">
<form class="form-inline" role="form" id="gh_save">
<div class="form-group">
<div class="col-xs-4">
<input type="text" placeholder="Github username" class="form-control" id="gh_user"/>
</div>
</div>
<div class="form-group">
<div class="col-xs-6">
<input type="text" placeholder="API Key" class="form-control" id="gh_apikey"/>
</div>
</div>
<div class="form-group">
<div class="col-xs-2">
<button type="submit" class="btn btn-success"> Save </button>
</div>
</div>
</form>
</div>

Answer 2

You should be able to target your ID within your css and set your desired width like so:
#gh_apikey{width:400px;}