app/views/tours/form_partials/_ar_file_upload.html.erb
<button class="btn btn-primary ar-file-upload-toggle mt-3" type="button">
Datei vom Computer hochladen
</button>
<input style="display: none" class="form-control-file ar-file-input" type="file">
<div class="upload-progress mt-3">
<div class="progress">
<div
class="progress-bar upload-progress-bar"
role="progressbar"
aria-valuenow="0"
aria-valuemin="0"
aria-valuemax="100">
</div>
</div>
</div>