ChristopherScott

That is tremendously helpful! I’ve added that code (although I’ve adjusted the width to 1024px) and resized all of my site’s thumbnails; all images now display properly. I haven’t noticed any issues with the rest of the site’s layout after implementing the fix.

It would be ideal if the theme itself were updated to correct this behaviour. Since it breaks basic WordPress functionality, I think it’s fair to consider it a bug. For now, I’ll have to use a child theme to force this fix.

I haven’t yet marked this topic as resolved since the theme itself still has this issue. Hopefully we’ll hear back from the developer.

If you would like to allow comments but just remove the “leave a comment” link on the main page, then consider adding the following code to your CSS stylesheet:

/*
* Hide the "Leave a comment" link on the front page.
*/
.comments-link {
display: none;
}

If you’re using Jetpack, add this under Appearance > Edit CSS so that your changes persist between theme updates.

As a general note, it’s my opinion that the “Leave a comment” link doesn’t make much sense for blogs that display excerpts on the main page. There’s not much reason to provide a link to the comment field before the reader has had a chance to read the post. Given that this is a relatively common use-case, it’s surprising that the theme bakes in that link and doesn’t provide a convenient way to remove it without disabling comments entirely, which is fairly extreme.

I have updated my site to use a child theme of Decode. I used the exact same code as copied above in the functions.php of the child theme, and the issue was resolved. I suspect that $content_width is first set outside of the functions.php file in the Decode theme.

I hope that this helps someone else having a similar issue!

I thought a little bit about how I might implement this, and here’s what came to mind (keep in mind, though, that my dev days are long behind me!):

My thinking is that a drop-down menu could be included on the Appearance > Customize pane for the theme that allows users to select an image resolution. The drop-down could be placed under “Content Options”, right after “Display a post’s featured image on its individual page”. The drop-down menu could be implemented with options such as “thumbnail”, “medium”, “large”, and “full” (which are all natively supported values for $size when calling the_post_thumbnail($size)).

One advantage of this approach is that users can set resolutions for “thumbnail”, “medium”, and “large” at Settings > Media, and these resolutions apply site-wide, so it gives them pretty flexible control over image sizes. You can even default to “full” and retain the current functionality, while providing an option to downscale for people who need it. Alternatively, instead of defaulting to “full”, you could add a new “header” image size (e.g. via add_image_size()), set it to an appropriate size for HiDPI displays (2048×2048 or ‘large’, whichever is bigger?), and use that as the default setting for featured images. That way, you’d be using a sensible resolution by default, and users could still change the size of the header through the drop-down menu if they need to.

For me, this sort of solution actually helps avoid messing with my images. Every other image on my site is in “large” resolution; if header images are the odd ones out, that’s an issue (especially if they’re very large images). By letting me choose the image size, that’s not messing with anything — that’s allowing my site to be consistent. If I hadn’t worked out a fix, I would have had to go through and destructively downscale all of my full-size header images (or remove featured images from each post), because using those images in their original full resolutions made my site nearly unusable.

Anyways, I hope you’ll consider implementing some sort of resolution-selection feature, whether or not it looks like the above! None of this is meant as a criticism — I really do love the theme. It’s pretty much perfect — it’s responsive, it offers flexible customization, and it has an attractive minimalist aesthetic. You’ve done fantastic work here.