MN-196 edit CSS for block recent_activity

Signed-off-by: Camille Tardy <camille.tardy@unige.ch>

scss/style_post_scss.scss

@@ -148,6 +148,16 @@ body {
       text-align: end;
     }
   }
+
+  //Blocks recent_activity
+  .block_recent_activity .activityhead {
+    margin-bottom: 15px;
+  }
+
+  .block_recent_activity h3 {
+    font-size: 0.95rem;
+    font-weight: 700;
+  }
 }
 
 // ---------------------------------------------------------------------------