OO-1843: prevent the preview images in "My courses" to be scaled by browsers

src/main/java/org/olat/repository/ui/RepositoryEntryImageMapper.java

@@ -60,7 +60,7 @@ public class RepositoryEntryImageMapper implements Mapper {
 				MetaInfo info = ((MetaTagged) image).getMetaInfo();
 				if(info != null) {
 					//121 is needed to fill the div
-					VFSLeaf thumbnail = info.getThumbnail(180, 121, true);
+					VFSLeaf thumbnail = info.getThumbnail(180, 120, true);
 					if(thumbnail != null) {
 						resource = new VFSMediaResource(thumbnail);
 					}

src/main/webapp/static/themes/light/modules/_coursesite.scss

@@ -40,6 +40,7 @@
 			margin-bottom: floor($line-height-computed / 2);
 			
 			.o_visual {
+				box-sizing: content-box;
 				border-right: 1px solid $o-coursesite-rowelem-border;		
 			}