These are good questions. Let me try to explain – it’s a bit technical, so bear with me. ??
1) Why wouldn’t it work to change the FP to 990×400 in the CSS Stylesheet Editor? Based on the language there it seems as though it would.
This is because of the way the the height for featured images that are used as the custom header is coded into the theme. This is this relevant function in /inc/custom-header.php:
function coraline_custom_header_setup() {
$args = array(
'default-image' => '%s/images/headers/water-drops.jpg',
'default-text-color' => '000',
'width' => apply_filters( 'coraline_header_image_width', 990 ),
'height' => apply_filters( 'coraline_header_image_height', 180 ),
'flex-height' => true,
'wp-head-callback' => 'coraline_header_style',
'admin-head-callback' => 'coraline_admin_header_style',
'admin-preview-callback' => 'coraline_admin_header_image',
);
The numbers you see there – 990 (width) and 180 (height) – are inserted right into the image tag, which you can see in the browser’s source for the page:
<img width="990" height="180" src="https://driftlessprairies.org/wp-content/uploads/2014/02/Bee-emerging-14featpic1.jpg" class="attachment-post-thumbnail wp-post-image" alt="Bee emerging (14){featpic}" />
The way HTML and CSS interact, CSS is not capable of overriding those values. The number 180 needs to be changed in the image tag itself, and that’s only possible with a child theme.
2) If I can figure out how to get the Style.CSS file that you had me write into the FTP, would that be sufficient to make this change? This would be a triage move then I could have time to actually learn what I’m doing.
The child theme has several parts, depending on what you’re trying to change. The style.css file needs to be in your child theme folder, as well as a functions.php file with the function I gave you earlier. If those two files are contained within your child theme folder, and everything is coded properly and in the right place, the new height on the featured image should work. You will also need to run the Regenerate Thumbnails plugin I mentioned earlier.
3) The only reason I’m working with FTP right now is because I could only get a folder (not a file) into the hosting site, right?
FTP is the usual method for uploading new files and folders to a server. Sometimes a hosting control panel lets you do these things, but in your case your host seems to be telling you there are some limitations.
