[help-wanted/beginner-friendly] Thumbnails not filling width on Mobile Devices

[lacymorrow]

The webpage is www.windstimme.at (a german Blog) and the problem is that on a mobile device (Android and iOS) the thumbnail picture is not fully scaled on the width of the blog.
The thumbnail appears to be much smaller and I don't know why. In the mobile view in Chrome or Firefox on my computer it works perfectly.

[lacymorrow]

Expected

[lacymorrow]

Seen:

[paulovsky]

This could be fixed if the theme would fetch a bigger version of the featured image, instead of its thumbnail.

[lacymorrow]

@paulovsky this seems like it is still an issue, yes?

I'm attempting an update for Jan 2018, I'll try and pull this ticket in.