I assume you have a Shortcode eg. [reading_time] in your element.
If so, the Add a new Headline Block, and were you would normally type some text, add the shortcode.
1. The author name container has a 5 px margin-bottom on the desktop, so in order to look the same, the reading time container’s margin-bottom should be set to 5px as well, it’s currently set to 9px.
2. The author name container’s line height is set to 24px, while the reading time container’s line height is set to 1em which is 14px. So try to set the reading time container’s line height to 24px.