How to achieve collapsing like in Bootstrap navigation for common DIVs?

Question

I have a 3-col-layout like

<div class="container">
    <div class="row">
        <div class="col-md-2" id="block1">#block1 .col-md-2</div>
        <div class="col-md-2" id="block2">#block2 .col-md-2</div>
        <div class="col-md-8" id="block3">#block3 .col-md-8</div>
    </div>
</div>

----------------------------------------------------------------
|          |          |                                        |
|          |          |                                        |
|          |          |                                        |
|          |          |                                        |
|  #block1 |  #block2 |                 #block3                |
|  .col-2  |  .col-2  |                 .col-8                 |
|          |          |                                        |
|          |          |                                        |
|          |          |                                        |
|          |          |                                        |
----------------------------------------------------------------

On small screens the columns slide one below the other:

-------------------------
|                       |
|                       |
|                       |
|                       |
|        #block1        |
|        .col-12        |
|                       |
|                       |
|                       |
|                       |
-------------------------
-------------------------
|                       |
|                       |
|                       |
|                       |
|        #block2        |
|        .col-12        |
|                       |
|                       |
|                       |
|                       |
-------------------------
-------------------------
|                       |
|                       |
|                       |
|                       |
|        #block3        |
|        .col-12        |
|                       |
|                       |
|                       |
|                       |
-------------------------

Now I want the first two columns to collapse like the typical Bootstrap navigation:

-------------------------
|   #block1 .col-12   ≡ |
-------------------------
-------------------------
|   #block2 .col-12   ≡ |
-------------------------
-------------------------
|                       |
|                       |
|                       |
|                       |
|                       |
|   #block3 .col-12     |
|                       |
|                       |
|                       |
|                       |
-------------------------

I tried to "clone" it from the Bootstrap starter template, but could not found out, what exactly manages this behavior.

How to get DIVs collapsing automatically on small screens and provide a toggle button? Is it possible to do this by using only Bootstrap classes (without additional JS)?

Answer 1

Here you go with a solution https://jsfiddle.net/mhmvhsf6/

.col{
  border: 1px dotted #000;
  min-height: 50px;
}

.collapse {
  height: 200px;
  background: rgba(0,0,0,0.3);
}

<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet"/>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<div class="container-fluid">
  <div class="row">
    <div class="col-xs-12 col-sm-12 col-md-4 col-lg-4 col">
      <div class="navbar-header navbar-inverse">
        <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#myNavbar">
          <span class="icon-bar"></span>
          <span class="icon-bar"></span>
          <span class="icon-bar"></span> 
        </button>
      </div>
      <div class="collapse navbar-collapse" id="myNavbar">
        
      </div>
    </div>
    <div class="col-xs-12 col-sm-12 col-md-4 col-lg-4 col">
      <div class="navbar-header navbar-inverse">
        <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#collapse2">
          <span class="icon-bar"></span>
          <span class="icon-bar"></span>
          <span class="icon-bar"></span> 
        </button>
      </div>
      <div class="collapse navbar-collapse" id="collapse2">
        
      </div>
    </div>
    <div class="col-xs-12 col-sm-12 col-md-4 col-lg-4 col"></div>
  </div>
</div>

Hope this will help you.

For Col-1 & col-2, content will go inside the collapse class container.