Fixes pour la mise à jour de mars (#598)

core/static/core/header.scss

@@ -196,10 +196,15 @@
           justify-content: flex-end;
         }
 
-        >a>img {
+        > a {
+          display: block;
           width: 40px;
           height: 40px;
           border-radius: 50%;
+          background-position: center center;
+          background-size: cover;
+          background-repeat: no-repeat;
+          background-color: #354a5f;
         }
 
         >.options {