diff --git a/xwiki-platform-core/xwiki-platform-image/xwiki-platform-image-lightbox/xwiki-platform-image-lightbox-ui/src/main/resources/XWiki/Lightbox/WebHome.xml b/xwiki-platform-core/xwiki-platform-image/xwiki-platform-image-lightbox/xwiki-platform-image-lightbox-ui/src/main/resources/XWiki/Lightbox/WebHome.xml
index 7f8f303d1b07..927584242466 100644
--- a/xwiki-platform-core/xwiki-platform-image/xwiki-platform-image-lightbox/xwiki-platform-image-lightbox-ui/src/main/resources/XWiki/Lightbox/WebHome.xml
+++ b/xwiki-platform-core/xwiki-platform-image/xwiki-platform-image-lightbox/xwiki-platform-image-lightbox-ui/src/main/resources/XWiki/Lightbox/WebHome.xml
@@ -513,7 +513,7 @@ bundles=blueimp-gallery,blueimp-helper,blueimp-gallery-fullscreen,blueimp-galler
   #set ($discard = $xwiki.linkx.use($services.webjars.url('org.xwiki.contrib:webjar-blueimp-gallery',
     'css/blueimp-gallery.min.css'), {'type': 'text/css', 'rel': 'stylesheet'}))
   #set ($discard = $xwiki.linkx.use($services.webjars.url('org.xwiki.platform:xwiki-platform-image-lightbox-webjar',
-    'less/lightbox.less', {'evaluate': true}), {'type': 'text/css', 'rel': 'stylesheet'}))
+    'lightbox.css'), {'type': 'text/css', 'rel': 'stylesheet'}))
   #set ($discard = $xwiki.jsx.use('XWiki.Lightbox.WebHome'))
   #set ($config = {})
   #set ($discard = $config.put('HTMLTemplate', "#lightboxHTMLTemplate"))
diff --git a/xwiki-platform-core/xwiki-platform-image/xwiki-platform-image-lightbox/xwiki-platform-image-lightbox-webjar/src/main/webjar/less/lightbox.less b/xwiki-platform-core/xwiki-platform-image/xwiki-platform-image-lightbox/xwiki-platform-image-lightbox-webjar/src/main/webjar/lightbox.css
similarity index 90%
rename from xwiki-platform-core/xwiki-platform-image/xwiki-platform-image-lightbox/xwiki-platform-image-lightbox-webjar/src/main/webjar/less/lightbox.less
rename to xwiki-platform-core/xwiki-platform-image/xwiki-platform-image-lightbox/xwiki-platform-image-lightbox-webjar/src/main/webjar/lightbox.css
index ee3104e7c4f3..5f4f5f9c4fb0 100644
--- a/xwiki-platform-core/xwiki-platform-image/xwiki-platform-image-lightbox/xwiki-platform-image-lightbox-webjar/src/main/webjar/less/lightbox.less
+++ b/xwiki-platform-core/xwiki-platform-image/xwiki-platform-image-lightbox/xwiki-platform-image-lightbox-webjar/src/main/webjar/lightbox.css
@@ -85,10 +85,10 @@
 }
 
 img + .lightbox-toggle {
-  min-width: @target-size-minimum;
-  min-height: @target-size-minimum;
+  min-width: var(--target-size-minimum);
+  min-height: var(--target-size-minimum);
   vertical-align: top;
-  margin: 0 0 0 -@target-size-minimum;
+  margin: 0 0 0 calc(-1 * var(--target-size-minimum));
 }
 
 #imageToolbarTemplate {
@@ -113,8 +113,8 @@ img + .lightbox-toggle {
       display: flex;
       align-items: center;
       justify-content: center;
-      min-width: @target-size-recommended;
-      min-height: @target-size-recommended;
+      min-width: var(--target-size-recommended);
+      min-height: var(--target-size-recommended);
     }
 
     .tooltip-inner {