A recipe page using CSS Flexbox

Nice work on the usage of semantic HTML tags and structuring your code.

In regards to the DRY principle I would suggest to avoid using id as a selector for the CSS styling where possible. An example includes:

#ingredients,
#instructions,
#nutrition {
  padding: 20px;
}

Instead, to create reusable styling you can do

.section-padding {
    padding: 20px
}

This way you can apply that CSS class to all the sections that require this styling without creating a bunch of IDs.