With Kosel theme, my layout is: 1000px.
I use the color scheme custom and after the custom palette: I change the background color to #808080 and it's OK for the body.
But the layout background color is always white.
How to change it also to #808080 ?

When I want edit a page with images, I read this  message:
Notice: A non well formed numeric value encountered

If I upload an image, I don't see the image and the message is:
Notice: A non well formed numeric value encountered in helpers.php,line48

It’s easy to create a child theme from one of the existing themes such as Boma.
    Create a new folder inside _themes and give it a short simple name. It’s best to use lower case letters and numbers only – no spaces. Let’s call it example.
    Copy the content of _themes/boma into your new folder.
    Edit _themes/example/config.ini. Change displayName to "Example" and change the description to whatever you like – but keep it short.

I use a child theme of Kosel and Juicebox Pro 1.5.0 with the name "album".
When I created it (copy of Kosel), the viewer settings was a little different. I customized again the viewer for my theme album.
Where are saved the viewer's settings for each different theme ?
With a future upgrade, how to keep my settings for the viewer?

I use Kosel theme Custom and I customize it.
It's possible to know where (or what file) are saved the new parameters (or css) of custom palette?

Edit: I found in the index.html

I will change the border color of name, email, message.
It's OK with this code for name and email (custom.css):

@media only screen and (min-width: 768px) {
  input[type=text],
  input[type=email] {
    width: 300px;
    border: 1px solid blue;  
  }
 }

But, it's difficult with "message". Can you help me?

Kosel theme has been optimized for images 1024x768 (FAQ).
I use a Canon 6d and if my resized images are 1024x683, should I change the size in Kosel to 1024x683?

I use pictures 900x600. All pictures and all galleries. Thumbnails (sqare 85x85) crop a little the image around the edges (keep center) but the quality is quite good.
Now if I want thumbnails rectangle 120x80 as the original picture, thumbnails crop more the image (around edges, top and bottom also) with less quality.
What can I do?

Theme Kosel, Customize theme, custom palette

When I modify colors (link or background or other), then save it and publish: no change!

What  I have forgotten?

Edit: sorry for this post. I just seen Overall color scheme, custom.