Read Aloud TTS crop + center + zoom selected region

**Description**

> What problem are we solving? What does the experience look like today? What are the symptoms? How can one reproduce the problem?

@cdrini as mentioned this before where recto and verso pages in one-up mode don't align correctly because they have different margins.

This problem is similar for text to speech which is that as the next region is selected the whole selected area is not cropped correctly in view so it's very hard to read along.

I should be able to listen to the TTS and read without having to change the zoom of the selected paragraph. The reader should handle this part of the experience for me and currently often clips for me on mobile.

**Evidence / Screenshot (if possible)**

> Include evidence of the problem or provide a screenshot.

**Expectation**

> What should be happening? What will it look like / how will it behave when fixed?

**Context**

> What operating system? What browser type and version?

**Proposal & Constraints**

> What is the proposed solution / implementation? Is there a precedent of this approach succeeding elsewhere?

**Stakeholders**

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