Not sure... if you add the link to your pen, I'd be happy to have a look
Here is the pen: "codepen.io/aggelow/pen/yxPBjW".
oh dear! that's because there's no size or position for the 'lighthouse-group' element. This is 100% my fault, I forgot this step in the tutorial (I've now amended the post). If you add the below CSS, and use the bottom property again, your issues should be fixed
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