ticket #37 : correction de "Les boutons de nouvelles calculettes sont tronqués sur petits écrans"

src/app/components/calculator-list/calculator-list.component.html

 <div class="container-fluid">
     <div class="row">
-        <div class="offset-4 col-4 mx-auto">
+        <div class="offset-1 col-10 mx-auto">
             <ul *ngFor="let l of _items" class="list-group">
                 <button class="list-group-item" (click)="create(l.type)">{{l.label}}</button>
             </ul>