Hi
I have the same problem like many others. In the “DWD Unwetter Binding” is the text of the description often to long for the Sitemap. So I searched for a solution.
I found some ideas, like put everythin in frames or something else. That was all not what I have seached for.
Now maybe I have a better solution.
I take via REST from the “Beschreibung” item the JSON value from “state” which is the description. The Transform this in a html file and display it with the webview in my sitemap.
The style is not perfect at the moment. And because I have never worked with html or css previously the code is probably not well.
This my code:
<!DOCTYPE html>
<html lang="en">
<style>
p {
color: rgb(92, 91, 91);
font-family: verdana;
font-weight: bolder;
font-size: 90%;
}
</style>
<head>
<title>JavaScript - read JSON from URL</title>
<script src="jquery.min.jsm"></script>
</head>
<body>
<p class="mypanel"></p>
<script>
$.getJSON('http://192.168.0.2:8080/rest/items/DWDBeschreibung', function(data) {
var text = `${data.state}`
$(".mypanel").html(text);
});
</script>
</body>
</html>
The local skript I´ve used is jquery. You can download it there:
https://jquery.com/download/
Then you have to save it in your openhab html folder.
Or refer to an online version of it: https://code.jquery.com/jquery-3.2.1.min.js
I prefere the local version 
ps sorry for my bad english, my school days are a long time ago 
