Ruby on rails - Bootstrap - 3 columns made responsive - css

Question

I have home page with following code:
<% #events.each_slice(3).to_a.each do |chunk| %>
<div class="row row-centered">
<% chunk.each do |event| %>
<div class="col-xs-12 col-sm-6 col-md-6 col-lg-4 col-centered">
centered content with max-width 300px
</div>
<% end %>
</div>
<% end %>
On big screen it works well. But when I change the size of browser, columns goes from 3 per row to 2 per row and the one left column goes to next row. So I have:
2 columns
1 column
2 columns
1 column
Is there any universal solution for responsive columns generated using #objects.each_slice(3)?

Answer 1

That's because you have the following classes:
col-xs-12 col-sm-6 col-md-6 col-lg-4
That means: 3 per row on a big screen, 2 per row on the middle screens, 1 per row on the mobile.
If you change to:
col-xs-12 col-sm-4 col-md-4 col-lg-4
This will make 3 per row on all the screens except from mobile where will be 1 per row.

Answer 2

So, my solution is pretty simple. On homepage I'll be showing exactly 12 posts. Given that, i changed my code to this:
<div class="row row-centered">
<% #events.each_slice(3).to_a.each do |chunk| %>
<% chunk.each do |event| %>
<div class="col-xs-12 col-sm-6 col-md-6 col-lg-4 col-centered">
<div class="thumbnail">
</div>
</div>
<% end %>
<% end %>
</div>
Given that I'm not generating row with 3 columns, but one row with 12 columns - and I let Bootstrap to deal with.

Answer 3

HTML example showing how Bootstrap responsive grids react to re-sizing
I wrote this HTML snippet to help whenever I want to figure out which combination of Bootstrap classes to use. It might help you too.
<div class="row">
<div class="page-header">
<h1>Bootstrap grid examples</h1>
<p class="lead">Basic grid layouts to get you familiar with building within the Bootstrap grid system.</p>
</div>
<h3>Three equal columns</h3>
<p>Get three equal-width columns <strong>starting at desktops and scaling to large desktops</strong>. On mobile devices, tablets and below, the columns will automatically stack.</p>
<div class="row">
<div class="col-md-4" style="background-color:red">.col-md-4</div>
<div class="col-md-4" style="background-color:pink">.col-md-4</div>
<div class="col-md-4" style="background-color:yellow">.col-md-4</div>
</div>
<h3>Three unequal columns</h3>
<p>Get three columns <strong>starting at desktops and scaling to large desktops</strong> of various widths. Remember, grid columns should add up to twelve for a single horizontal block. More than that, and columns start stacking no matter the viewport.</p>
<div class="row">
<div class="col-md-3" style="background-color:red">.col-md-3</div>
<div class="col-md-6" style="background-color:pink">.col-md-6</div>
<div class="col-md-3" style="background-color:yellow">.col-md-3</div>
</div>
<h3>Two columns</h3>
<p>Get two columns <strong>starting at desktops and scaling to large desktops</strong>.</p>
<div class="row">
<div class="col-md-8" style="background-color:pink">.col-md-8</div>
<div class="col-md-4" style="background-color:yellow">.col-md-4</div>
</div>
<h3>Two columns with two nested columns</h3>
<p>Per the documentation, nesting is easy, just put a row of columns within an existing column.</p> <p>This gives you two columns <strong>starting at desktops and scaling to large desktops</strong>, with another two (equal widths) within the larger column.</p>
<p>At mobile device sizes, tablets and down, these columns and their nested columns will stack.</p>
<div class="row">
<div class="col-md-8" style="background-color:yellow">
.col-md-8
<div class="row">
<div class="col-md-6" style="background-color:lightgreen">.col-md-6</div>
<div class="col-md-6" style="background-color:pink">.col-md-6</div>
</div>
</div>
<div class="col-md-4" style="background-color:lightgray">.col-md-4</div>
</div>
<h3>Full width, single column</h3>
<p class="text-warning">No grid classes are necessary for full-width elements.</p>
<h3>Mixed: mobile and desktop</h3>
<p>The Bootstrap 3 grid system has four tiers of classes: xs (phones), sm (tablets), md (desktops), and lg (larger desktops). You can use nearly any combination of these classes to create more dynamic and flexible layouts.</p>
<p>Each tier of classes scales up, meaning if you plan on setting the same widths for xs and sm, you only need to specify xs.</p>
<div class="row">
<div class="col-xs-12 col-md-8" style="background-color:red">.col-xs-12 .col-md-8</div>
<div class="col-xs-6 col-md-4" style="background-color:lightgray">.col-xs-6 .col-md-4</div>
</div>
<div class="row">
<div class="col-xs-6 col-md-4" style="background-color:lightgray">.col-xs-6 .col-md-4</div>
<div class="col-xs-6 col-md-4" style="background-color:yellow">.col-xs-6 .col-md-4</div>
<div class="col-xs-6 col-md-4" style="background-color:lightgreen">.col-xs-6 .col-md-4</div>
</div>
<div class="row">
<div class="col-xs-6" style="background-color:lightgray">.col-xs-6 </div>
<div class="col-xs-6" style="background-color:lightgreen">.col-xs-6</div>
</div>
<hr>
<h3>Mixed: mobile, tablet, and desktop</h3>
<div class="row">
<div class="col-xs-12 col-sm-6 col-lg-8" style="background-color:lightgray">.col-xs-12 .col-sm-6 .col-lg-8</div>
<div class="col-xs-6 col-lg-4" style="background-color:yellow">.col-xs-6 .col-lg-4</div>
</div>
<div class="row">
<div class="col-xs-6 col-sm-4" style="background-color:lightgreen">.col-xs-6 .col-sm-4</div>
<div class="col-xs-6 col-sm-4" style="background-color:pink">.col-xs-6 .col-sm-4</div>
<div class="col-xs-6 col-sm-4" style="background-color:lightgray">.col-xs-6 .col-sm-4</div>
</div>
<hr>
<h3>Column clearing</h3>
<div class="row">
<div class="col-xs-6 col-sm-3" style="background-color:lightgray">
.col-xs-6 .col-sm-3
<br>
Resize your viewport or check it out on your phone for an example.
</div>
<div class="col-xs-6 col-sm-3" style="background-color:yellow">.col-xs-6 .col-sm-3</div>
<!-- Add the extra clearfix for only the required viewport -->
<div class="clearfix visible-xs"></div>
<div class="col-xs-6 col-sm-3" style="background-color:lightgreen">.col-xs-6 .col-sm-3</div>
<div class="col-xs-6 col-sm-3" style="background-color:pink">.col-xs-6 .col-sm-3</div>
</div>
<hr>
<h3>Offset, push, and pull resets</h3>
<p>Reset offsets, pushes, and pulls at specific breakpoints.</p>
<div class="row">
<div class="col-sm-5 col-md-6" style="background-color:lightgray">.col-sm-5 .col-md-6</div>
<div class="col-sm-5 col-sm-offset-2 col-md-6 col-md-offset-0" style="background-color:yellow">.col-sm-5 .col-sm-offset-2 .col-md-6 .col-md-offset-0</div>
</div>
<div class="row">
<div class="col-sm-6 col-md-5 col-lg-6" style="background-color:lightgreen">.col-sm-6 .col-md-5 .col-lg-6</div>
<div class="col-sm-6 col-md-5 col-md-offset-2 col-lg-6 col-lg-offset-0" style="background-color:pink"<>.col-sm-6 .col-md-5 .col-md-offset-2 .col-lg-6 .col-lg-offset-0" </div>
</div>
</div>