Hi Pieter Paulussen,

You add a class to your date time filed and write a script. Then include maxlength property to the date to remove from right side.

For example

<script type="text/javascript">
     $('.your_date_field').css({"color": "red", "border": "2px solid red"});//TO TEST
     // CODE WHEN READ ONLY
     //CODE WHEN EDIT
</script>
<field name="date" class="your_date_field"/>