Picture not loaded

[paucazou]

I've just installed your wonderful script but I found some issues.
The first one is the following : on some websites, such as http://slackware.com ,the background picture doesn't appear. On the contrary, it is possible to load the picture itself when I enter the URl of the picture herself (http://www.slackware.com/grfx/shared/background.jpg)
I found that on some other websites.

Configuration:
Debian Buster
Nginx 1.10.3
PHP 7.0.33-0+deb9u10

Thanks in advance !