start writing letter head with kundennummer, rechnungsnummer and rechnungsdatum

test_data/RG004711.yaml

@@ -1,3 +1,4 @@
+#Id: RG004712
 CustomerId: KD01234
 #InvoiceDate: 2023-12-23
 

test_data/templates/invoice.html

@@ -42,6 +42,7 @@
         #letter_head_content {
             background-color: lightblue;
         }
+
     </style>
 </head>
 
@@ -57,15 +58,30 @@
 </div>
 <div id="letter_head_content">
     {% for address in envelope.AddressContent.Contents %}
-            {% if address.Head %}
+    {% if address.Head %}
     <p><strong>{{ address.Head }}</strong></p>
-            {% endif %}
+    {% endif %}
     <p>{{ address.Text | replace('\n', '<br>') }}</p>
     {% endfor %}
 </div>
 
 
 <!-- HTML Content -->
+<table>
+    <tr>
+        <td>Rechnungsnummer:</td>
+        <td>Kundennummer:</td>
+        <td>Rechnungsdatum:</td>
+    </tr>
+    <tr>
+        <td>{{ invoice.Id }}</td>
+        <td>{{ invoice.CustomerId }}</td>
+        <td>{{ invoice.InvoiceDate }}</td>
+    </tr>
+    </tr>
+</table>
+
+
 To PDF or not to PDF
 
 <section>