I installed the let´s encrypt certificate on server and the https in not gree color and with note SECURE, but gray with information: “Attachers might be able to see the images you have looking at on this site and trick you by modifing them.”
Is it eshop in prestashop - https://e-smoke.sk/
I have inslated other cestificated in other prestashop eshops withuout any problem , so I do not know what could be the problem.
This is a “Mixed Content” problem. The certificate is fine, but one or more of the images linked in the page don’t come through HTTPS. There may also be web forms on some pages that are insecure for the same reason.
Try asking https://whynopadlock.com about your site, or if you use particular software to build the site, look for information about “Mixed Content” with the software you use and how to fix it.