@kr_noob Continuing conversation from your comment here, this is the thread for such things.
If you can do it with a jinja template then you can add it to Custom Header, I am no Jinja expert and I just don’t have the time to write Jinja for anyone that requests it. This is why I often mention that this feature (complex html, css, and other fancy templates) is unsupported and isn’t really a feature at all. It’s more of a side effect of how things are rendered in CH.
All that being said, you would need to parse the JSON from the sensor you are using and the template section of the developer tools in HA is a great place to start. It even has an example of JSON parsing in the default template it shows. I can give you a bit of a head start, but making this work in the template that you are using would be up to you.
Go to developer tools >> templates and paste in the following example to see how to pull just the titles from the JSON in your feedparser sensor.
This will show the first 3 titles pulled from the sensor:
{{ state_attr('sensor.npr', 'entries')[0].title }}
{{ state_attr('sensor.npr', 'entries')[1].title }}
{{ state_attr('sensor.npr', 'entries')[2].title }}