Remove individual modal width styles

app/assets/stylesheets/framework/modal.scss

@@ -16,6 +16,8 @@ body.modal-open {
   overflow: hidden;
 }
 
-.modal .modal-dialog {
+@media (min-width: $screen-md-min) {
+  .modal-dialog {
     width: 860px;
+  }
 }

app/assets/stylesheets/pages/merge_requests.scss

@@ -319,8 +319,6 @@
 }
 
 #modal_merge_info .modal-dialog {
-  width: 600px;
-
   .dark {
     margin-right: 40px;
   }

app/assets/stylesheets/pages/tree.scss

@@ -145,8 +145,6 @@
   margin: 0;
 }
 
-#modal-remove-blob > .modal-dialog { width: 850px; }
-
 .blob-upload-dropzone-previews {
   text-align: center;
   border: 2px;