diff --git a/src/app/additional-field/additional-field.component.html b/src/app/additional-field/additional-field.component.html
index 1cbb6ba..ae7d6aa 100644
--- a/src/app/additional-field/additional-field.component.html
+++ b/src/app/additional-field/additional-field.component.html
@@ -9,7 +9,7 @@
       <ng-select *ngSwitchCase="'country'" [attr.id]="ticketUUID + '-' + field.name" formControlName="0" appInvalidFeedback [items]="countries" bindLabel="name" bindValue="isoCode" [inputAttrs]="{autocomplete: 'nope'}">
         <ng-template ng-notfound-tmp let-searchTerm="searchTerm"></ng-template>
       </ng-select>
-      <select *ngSwitchCase="'select'" [attr.id]="ticketUUID + '-' + field.name" class="custom-select" formControlName="0" appInvalidFeedback>
+      <select *ngSwitchCase="'select'" [attr.id]="ticketUUID + '-' + field.name" class="form-select" formControlName="0" appInvalidFeedback>
           <option value=""></option>
           <option *ngFor="let c of field.restrictedValues" [ngValue]="c">{{getRestrictedValueLabel(c)}}</option>
       </select>
diff --git a/src/app/additional-service-quantity-selector/additional-service-quantity-selector.html b/src/app/additional-service-quantity-selector/additional-service-quantity-selector.html
index 8b89a00..8edc795 100644
--- a/src/app/additional-service-quantity-selector/additional-service-quantity-selector.html
+++ b/src/app/additional-service-quantity-selector/additional-service-quantity-selector.html
@@ -5,7 +5,7 @@
     <input type="number" min="0" step="1" class="form-control" placeholder="0" autocomplete="off" formControlName="quantity" [id]="'additional-'+additionalService.id+'-qty'">
   </div>
   <div *ngIf="additionalService.fixPrice && [null, 'OPTIONAL_MAX_AMOUNT_PER_RESERVATION', 'OPTIONAL_MAX_AMOUNT_PER_TICKET'].indexOf(additionalService.supplementPolicy) >= 0 ">
-    <select class="custom-select text-align-center" placeholder="0" autocomplete="off" formControlName="quantity" [id]="'additional-'+additionalService.id+'-qty'">
+    <select class="form-select text-align-center" placeholder="0" autocomplete="off" formControlName="quantity" [id]="'additional-'+additionalService.id+'-qty'">
       <option *ngFor="let amount of validSelectionValues" [ngValue]="amount">{{amount}}</option>
     </select>
   </div>
diff --git a/src/app/event-display/event-display.component.html b/src/app/event-display/event-display.component.html
index e45a9fe..90a3bed 100644
--- a/src/app/event-display/event-display.component.html
+++ b/src/app/event-display/event-display.component.html
@@ -53,14 +53,14 @@ <h4 translate="show-event.sold-out.message"></h4>
           </div>
           <div class="form-group" *ngIf="ticketCategoriesForWaitingList && ticketCategoriesForWaitingList.length > 1">
             <label for="selectedCategory" translate="reservation-page.category"></label>
-            <select name="selectedCategory" id="selectedCategory" formControlName="selectedCategory" class="custom-select" appInvalidFeedback>
+            <select name="selectedCategory" id="selectedCategory" formControlName="selectedCategory" class="form-select" appInvalidFeedback>
               <option value=""></option>
               <option *ngFor="let tc of ticketCategoriesForWaitingList" [ngValue]="tc.id">{{tc.name}}</option>
             </select>
           </div>
           <div class="form-group">
               <label for="userLanguage" translate="reservation-page-complete.language"></label>
-              <select name="userLanguage" formControlName="userLanguage" id="userLanguage" class="custom-select" required="required" aria-required="true" appInvalidFeedback>
+              <select name="userLanguage" formControlName="userLanguage" id="userLanguage" class="form-select" required="required" aria-required="true" appInvalidFeedback>
                 <option value=""></option>
                 <option *ngFor="let l of event.contentLanguages" [ngValue]="l.locale">{{l.displayLanguage}}</option>
               </select>
diff --git a/src/app/reservation/invoice-form/invoice-form.component.html b/src/app/reservation/invoice-form/invoice-form.component.html
index fb10a95..4073366 100644
--- a/src/app/reservation/invoice-form/invoice-form.component.html
+++ b/src/app/reservation/invoice-form/invoice-form.component.html
@@ -130,7 +130,7 @@ <h2 translate="reservation-page.invoice-details"></h2>
       <div class="col-12 col-md-6">
         <div class="form-group">
           <label for="italyEInvoicingReferenceType">{{'invoice-fields.addresseeItalyEInvoice' | translate}}{{' *'}}</label>
-          <select class="custom-select" id="italyEInvoicingReferenceType" required aria-required="true" formControlName="italyEInvoicingReferenceType">
+          <select class="form-select" id="italyEInvoicingReferenceType" required aria-required="true" formControlName="italyEInvoicingReferenceType">
             <option value="ADDRESSEE_CODE" translate="invoice-fields.addressee-code"></option>
             <option value="PEC" translate="invoice-fields.pec"></option>
             <option value="NONE" translate="invoice.fields.neither"></option>
diff --git a/src/app/reservation/ticket-form/ticket-form.component.html b/src/app/reservation/ticket-form/ticket-form.component.html
index f3647df..843df87 100644
--- a/src/app/reservation/ticket-form/ticket-form.component.html
+++ b/src/app/reservation/ticket-form/ticket-form.component.html
@@ -30,7 +30,7 @@
 
     <div class="form-group" *ngIf="purchaseContext && purchaseContext.contentLanguages.length > 1">
       <label [attr.for]="ticket.uuid + '-userLanguage'" translate="reservation-page-complete.language"></label>
-      <select [attr.id]="ticket.uuid + '-userLanguage'" formControlName="userLanguage" class="custom-select" appInvalidFeedback>
+      <select [attr.id]="ticket.uuid + '-userLanguage'" formControlName="userLanguage" class="form-select" appInvalidFeedback>
         <option value=""></option>
         <option *ngFor="let lang of purchaseContext.contentLanguages" [ngValue]="lang.locale">{{lang.displayLanguage}}</option>
       </select>
diff --git a/src/app/ticket-quantity-selector/ticket-quantity-selector.html b/src/app/ticket-quantity-selector/ticket-quantity-selector.html
index df4cf87..f1f5536 100644
--- a/src/app/ticket-quantity-selector/ticket-quantity-selector.html
+++ b/src/app/ticket-quantity-selector/ticket-quantity-selector.html
@@ -1,7 +1,7 @@
 <div [formGroup]="parentGroup">
   <ng-container *ngIf="category.saleableAndLimitNotReached">
     <label class="sr-only" [for]="'category-'+category.id+'-qty'" translate="show-event.category.quantity"></label>
-    <select [id]="'category-'+category.id+'-qty'" formControlName="amount" class="custom-select" (change)="selectionChanged()">
+    <select [id]="'category-'+category.id+'-qty'" formControlName="amount" class="form-select" (change)="selectionChanged()">
       <option *ngFor="let qty of quantityRange" [ngValue]="qty">{{qty}}</option>
     </select>
   </ng-container>