bootstrap grid
<!----------------------- BOOTSTRAP GRID SYSTEM ------------------------>
This code will create 4 boxes placed side by side, which will be
dynamically positioned, according to the size of the screen. We define
the following behavior:
<!-- Desktop Display: we have 4 columns per row (each occupies 3 units out of 12) -->
class = "col-lg-3" <!-- display large with 12/3 = 4 columns -->
<!-- Tablet Display: we have 3 columns per row (each occupies 4 units out of 12) -->
class = "col-md-4" <!-- display medium with 12/4 = 3 columns -->
<!-- Mobile Display: we have 2 columns per row (each occupies the 6 units of 12) -->
class = "col-sm-6" <!-- display small with 12/6 = 2 columns -->
<!-- CODE -->
<div class="row">
<div class="col-lg-3 col-md-4 col-sm-6" style="background-color:red; border:1px solid black;">
One of four columns
</div>
<div class="col-lg-3 col-md-4 col-sm-6" style="background-color:yellow; border:1px solid black;">
One of four columns
</div>
<div class="col-lg-3 col-md-4 col-sm-6" style="background-color:green; border:1px solid black;">
One of four columns
</div>
<div class="col-lg-3 col-md-4 col-sm-6" style="border:1px solid black;">
One of four columns
</div>
</div>