Is my code wrong, or there is a bug in opencart - php

Question

I've created extremely simple module for Opencart, just displaying hello world in the admin panel. Here is my controller:
<?php
class ControllerExtensionModuleHelloworld extends Controller {
public function index(){
$this->load->language('/extension/module/helloworld');
$this->document->setTitle('Hello World');
$data['heading_title'] = $this->language->get('heading_title');
$data['helloworld'] = $this->language->get('helloworld');
$data['header'] = $this->load->controller('common/header');
$data['column_left'] = $this->load->controller('common/column_left');
$data['footer'] = $this->load->controller('common/footer');
$this->response->setOutput($this->load->view('extension/module/helloworld', $data));
}
}
Here is my view:
{{header}}
<div class="container">
<div class="row>
<div class="col">
{{column_left}}
</div>
<div class="col">
<h1>{{heading_title}}</h1>
<p>{{helloworld}}</p>
</div>
</div>
</div>
{{footer}}
The problem is that the h1 and the p tags are displayed under the the column-left like this:
I changed the col classes with col-sm-4 and col-sm-8 like this:
{{header}}
<div class="container">
<div class="row>
<div class="col-sm-3">
{{column_left}}
</div>
<div class="col-sm-8">
<h1>{{heading_title}}</h1>
<p>{{helloworld}}</p>
</div>
</div>
</div>
{{footer}}
But this didn't work, finally I added col-sm-offset-2 class to the col-sm-8 div, and it shifted the text left, like it's suppose to be.
Any ideas where the problem may be?

Answer 1

{{ header }} {{column_left}}
<div id="content">
<div class="page-header">
<div class="container-fluid">
<h1>{{ heading_title }}</h1>
</div>
</div>
<div class="container-fluid">
<!-- content here -->
</div>
</div>
{{ footer }}
Try this, it should work.