Dynamic textbox with centered text but only expanding to the left

Hi everyone,

I'm trying to create a text box with two lines of text (headline and subline). The box should grow with the text, wichever of the two lines of text is longer. I've gotten this far but now I'm stuck.

The box must only expand to the left, keeping it anchored to a fixed place on the right side. Also, the two lines of text must remain centered within the box. I can't really wrap my head around how this could be done. Any help is highly appreciated.

Tanks a lot.