Fix avatar offset on PR/issue timeline view (#13753)

* Fix avatar offset on PR/issue timeline view

* Apply suggestions from code review

Co-authored-by: silverwind <me@silverwind.io>

Co-authored-by: silverwind <me@silverwind.io>

web_src/less/_repository.less

@@ -837,8 +837,6 @@
           width: 20px;
           height: 20px;
           margin-right: .5rem;
-          position: relative;
-          top: -2px;
         }
 
         &:first-child:not(.commit) {
@@ -894,6 +892,12 @@
           .singular-commit {
             line-height: 34px; /* this must be same as .badge height, to avoid overflow */
 
+            > .avatar.image,
+            > .avatar.image img {
+              position: relative;
+              top: -2px;
+            }
+
             .shabox {
               .sha.label {
                 margin: 0;