Ryan Kienstra

<ul>
<li>Must have Twitter Bootstrap 3 and Glyphicons.</li>
<li>Drag and drop 1-4 widgets in each horizontal row.</li>
<li>Easy: each widget has a button to edit, add, delete.</li>
<li>Build an entire page with widgets.</li>
<li>Approve changes before publishing them.</li>
<li>Works with themes “evolve,” “Unite,” and “DevDmBootstrap3.”</li>
<li>Works with “Openstrap,” but icons are unclear.</li>
</ul>
<span class="embed-youtube" style="text-align:center; display: block;"><iframe loading="lazy" class="youtube-player" width="640" height="360" src="https://www.youtube.com/embed/xIAAr8MLpJ0?version=3&rel=1&showsearch=0&showinfo=1&iv_load_policy=1&fs=1&hl=en-US&autohide=2&wmode=transparent" allowfullscreen="true" style="border:0;" sandbox="allow-scripts allow-same-origin allow-popups allow-presentation allow-popups-to-escape-sandbox"></iframe></span>
<p>Setup:<br />
<span class="embed-youtube" style="text-align:center; display: block;"><iframe loading="lazy" class="youtube-player" width="640" height="360" src="https://www.youtube.com/embed/OeSU8EMSgDY?version=3&rel=1&showsearch=0&showinfo=1&iv_load_policy=1&fs=1&hl=en-US&autohide=2&wmode=transparent" allowfullscreen="true" style="border:0;" sandbox="allow-scripts allow-same-origin allow-popups allow-presentation allow-popups-to-escape-sandbox"></iframe></span></p>


Adapter Widget Rows

Drag and drop widgets on your full screen. They'll fit into horizontal rows, and re-size on mobile devices. Create up to 6 rows.

Trevor Anderson

<p>Split sidebars and widget areas into responsive columns.</p>
<p>Two simple widgets are provided, “Layout: New Column” and “Layout: New Column on New Row”.</p>
<p>Simply place these in your widget area where you’d like to create a new column (split) or new row of columns.</p>
<p>Gutter size and responsive collapse options are available in the Customizer -> Widget Columns panel.</p>


Tuxedo Responsive Widget Columns

Just tested this plugin, and it works exactly as I hoped for. I can now have complex layouts in any widget areas. 
Of course it's best used for horizontal widget areas like footers, etc...



Works perfectly!

Split sidebars and widget areas into responsive columns.

Adapter Widget Rows vs Tuxedo Responsive Widget Columns