<strong>However,</strong> they
do not allow for alpha transparency in the fill. For technical reasons,
we can have changing fill colors or transparency but not both.</p>
<p>Here is a simple example of changing fill colors with
<code>geom_ridgeline_gradient</code>:</p>
<div class="sourceCode" id="cb13"><pre class="downlit sourceCode r">
<code class="sourceCode R"><span><span class="va">d</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/base/data.frame.html" class="external-lin