Fix width of gas customization model in notification view

ui/app/components/gas-customization/gas-modal-page-container/index.scss

@@ -8,8 +8,6 @@
     overflow-y: initial;
 
     @media screen and (max-width: $break-small) {
-      max-width: 344px;
-
       &__content {
         display: flex;
         overflow-y: initial;

ui/app/components/gas-customization/gas-price-button-group/index.scss

@@ -65,7 +65,10 @@
 .gas-price-button-group--small {
   display: flex;
   justify-content: stretch;
-  max-width: 260px;
+
+  @media screen and (max-width: $break-small) {
+    max-width: 260px;
+  }
 
   &__button-fiat-price {
     font-size: 13px;