Parens inside of parens doesn't work here. Just renders the text on the website, not the link. This is a simple solution that still redirects correctly to Wikipedia.
{% include elements/anchor.html name="Responsive images with ratios" %}
<div class="content">
- <p>If you don't know the exact dimensions but know the <strong>ratio</strong> instead, you can use one of the <strong>16 ratio modifiers</strong>, which include [common aspect ratios in still photography](https://en.wikipedia.org/wiki/Aspect_ratio_(image)#Still_photography):</p>
+ <p>If you don't know the exact dimensions but know the <strong>ratio</strong> instead, you can use one of the <strong>16 ratio modifiers</strong>, which include [common aspect ratios in still photography](https://en.wikipedia.org/wiki/Aspect_ratio_%28image%29#Still_photography):</p>
</div>
<table id="images" class="table is-bordered">