Use Set Style Attribute to set CSS attributes of a display element, such as text style, colors etc. Using it to set the actual text displayed might be possible, but is not the recommended method, and in any case, you should not add an ancestor reference inside Set Style Attribute.
You should rather do the following:
1. Setting text
To set the text you would model as follows:
Note that the 'New Text' flows into the <Value> text element, not to the 'Old Text' constant.
2. Setting style
There are various ways to set or update the style of a display, one of which is using via Set Style Attribute, as in the following screenshot:
Note that we're passing a reference to the display element itself to the <Element> trigger.
Alternate methods for setting the style are:
For more information on CSS and other design aspects see here @ here.
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