How about
<div class="input-group input-group-sm">
<span class="input-group-btn btn-group-custom">
<button id="ButtonCreate" class="btn btn-default btn-sm" onclick="CreateItem()" title="Erstellen"><span class="glyphicon glyphicon-file"></span></button>
<button id="ButtonUpdate" class="btn btn-default btn-sm" onclick="UpdateItem()" title="Bearbeiten"><span class="glyphicon glyphicon-pencil"></span></button>
<button id="ButtonDelete" class="btn btn-default btn-sm" onclick="DeleteItems()" title="Löschen"><span class="glyphicon glyphicon-trash"></span></button>
<button id="ButtonExport" class="btn btn-default btn-sm" onclick="ExportItems()" title="Exportieren"><span class="glyphicon glyphicon-export"></span></button>
<button id="ButtonSearch" class="btn btn-default btn-sm" onclick="SearchItem()" title="Suchen"><span class="glyphicon glyphicon-search"></span></button>
</span>
<input class="form-control" style="width: 300px;" placeholder="Suchen" type="text">
</div>
You need to manually collapse borders and tweek them on hover and for the visaul space:
.btn-group-custom .btn {
border-right-width: 0;
}
.btn-group-custom .btn:hover {
border-right-width: 1px;
}
.btn-group-custom .btn:hover + .btn {
border-left-width: 0;
}
#ButtonSearch {
border-left-width: 1px;
border-right-width: 0;
margin-left: 16px;
}
#ButtonExport {
border-right-width: 1px;
}