Having 3 Fixed column layout

Question

I have 3 fixed columns of width 300px to be placed under a container of 960 px. I used bootstrap 2.3.2 but figuring out that bootstrap 3 in mobile first, I switched to it. This is the current structure I am using

<div class="container">
    <div class="row">
        <div class="col-lg-8 col-md-8 col-sm-12">
            <div class="row">
                    <div class="col-lg-6 col-md-6"> 
                    </div>
                    <div class="col-lg-6 col-md-6"> 
                    </div>
                </div>
                <div class="row">
                    <div class="col-lg-6 col-md-6"> 
                    </div>
                    <div class="col-lg-6 col-md-6"> 
                    </div>
                </div>

                    <div class="row">
                    <div class="col-lg-6 col-md-6"> 
                    </div>
                    <div class="col-lg-6 col-md-6"> 
                    </div>
                </div>

                <div class="row">
                    <div class="col-lg-6 col-md-6">         
                    </div>
                    <div class="col-lg-6 col-md-6"> 
                    </div>
                </div>
            </div>

        <div class="col-lg-4 col-md-4 col-sm-12">
            <div class="row">
                <div class="col-lg-12 col-md-12">       
                </div>
                <div class="col-lg-12 col-md-12">               
                     </div>
                <div class="col-lg-12 col-md-12">                       
                </div>
                    <div class="col-lg-12 col-md-12">
                </div>
                <div class="col-lg-12 col-md-12">   
                </div>
                <div class="col-lg-12 col-md-12">                       
                </div>
                <div class="col-lg-12 col-md-12 facebookActivity">
                </div>
            </div>
        </div>
    </div>

For the CSS

        @media (min-width: 1200px) {
                    .container {
                        width: 960px;
            }
        }

Everything is coming under one single column. What is the best way to achieve this? 3 columns of 300px in desktop, 2 columns in tablet (adjusting the padding) and 1 column in mobile.

so a layout would be 15px - 300 - 15px - 300 -15px - 300 - 15px

Answer 1

Try this BOOTPLY

<div class="container">
  <div class="row">
      <div class="col-md-4 col-sm-6 col-xs-12">
        <div></div>
      </div>
      <div class="col-md-4 col-sm-6 col-xs-12">
          <div></div>
    </div>
      <div class="col-md-4 col-sm-6 col-xs-12">
          <div></div>
    </div>
</div></div>