Version 6.9.5

Can confirm that I have tried with addition to my [media/blogs/***/style.css] with no effect and by checking source code no parameters were added to the image element.

Somehow by removing links and replacing I have css selectors so I tried this, which worked, but my selector wasn't added

a#link_45 img.evo_thumbnail{border: 3px solid green}

The correct syntax is

[image:18:-:.redborder]

as per: http://b2evolution.net/man/image-short-tag

Does that mean the syntax used in http://b2evolution.net/man/thumbnail-short-tag is incorrect, as it doesn't work?
[thumbnail:345:large:left:.redborder]
So what is the [:-:] for?

[image:ID:title:classname]

[:-:] the dash between the colons are meant to be the title

class name starts with .

the : separates the fields

[PART1:PART2:PART3:PART4]

PART1 == image
PART2 == image file ID
PART3 == Caption / Title
PART4 == CSS CLASSNAME

anyway, I am sorry that does not work. I tried it in b2e demo using blog A and copying the style as described in http://b2evolution.net/man/image-short-tag

@amoun the syntax for image and for thumbnail is different.

@saunders the syntax for image and for thumbnail is different. Your screenshot shows you tried to use one with the other.

@fplanque wrote earlier:

@amoun the syntax for image and for thumbnail is different.

@saunders the syntax for image and for thumbnail is different. Your screenshot shows you tried to use one with the other.

AH!

@fplanque Is there a way to define a class for image set to "Cover" or "after more" ? (e.g. .redborder)

Probably but in that case you have to dig into your CSS explorer to find the correct CSS selector.