Try this link...
I think you missed the last digit (i.e. 8) off of the link you posted.
You are right indeed. You have to find the template node named "Slideshow Grid" and do a small change on it.
<style>
#Slide_Slideshow .nr-dashboard-template {
background-image : url(/slideshow/{{payload}});
background-repeat: no-repeat;
background-position: center;
background-size: cover;
}
</style>
It is hardcoded to work with a tab named "Slide" and group named "Slideshow". Change the first line inside the style tag to fit your TAB_Group. In the very same line use the CSS selector ".nr-dashboard-template" as it is more specific then the one used previously (md-card). I will add this explanation to the flow posted in the Library.
Thanks @Andrei . It did work after changed as you mentioned.
to recap for future:
Changing the below line in the "Slideshow Grid" node in the flow
#Slide_Slideshow md-card {
to
#TAB_GROUP .nr-dashboard-template {
where TAB is the the tab name. And, GROUP is the group name.
Dashboard slideshow
This flow based on the @Andrei flow above :
creates a slideshow in the Dashboard with pictures from a local directory in your Raspberry pi. The slideshow is controlled by nod-red dashboard buttons.
Features
- You can play and pause the slideshow. Go to next/previous , last/first.
- The time each picture displays is configurable in a delay node.
- You can delete pictures.
See the complete topic in the #share-your-projects area : Dashboard slideshow gallery
Probably best to cut/paste just that last post into the #share-your-projects area
yes i will 
Thank you @SuperNinja and @Andrei for good word. There is a minor side effect (not critical). Requiring the name of the TAB and GROUP names within the CSS will create a small limitation. It is limiting the user to write the TAB and GROUP names in English only 
Hi @newbie for my part, I do not use images in the background, they are displayed as images that can be resized, arranged, as desired in the "web page". I do not modify the CSS.
For testing , use this classic html code:
<style>
img {
width: 100%;
height: auto;
}
</style>
<body>
<div >
<img src= "/camAlerte/{{msg.fileName}}" alt="Camera Picture" ><br>
</div>
</body>
Where msg.fileName is the name of the file to display Ex: car.jpg send by the previous node.
Of course , change camAlerte by your folder
Try it out.
I will try. Thanks @SuperNinja
Take a look at the complete project :
@SuperNinja, Thanks again. You are right. It did work very well regardless of the language. I will modify my comments. I encountered two small obstacles (maybe because I use windows environment). I will write them in the project page.
Edit (correction) : @SuperNinja work is independent from interface language.
@SuperNinja Thanks again, regarding the small obstacle (only one ) . It is the path of images. In windows, the path type in DIRECTORY node (fs-op-dir node) should be string as shown in image below to work. Hence, we may benefit from @Andrei work to implement the path directly and not using SET PATH node.
That is it
