RichText editor height

I can get a richtext editor onto a Modern UI screen, or at least a box that displays html, I can’t seem to find any way to control the height of the text area.  I need to to be at least 500px high.

I attempted to add the class stretch, but it didn’t work.

HTML / TS

<template>
  <qp-fieldset id="Document_PXLayoutRule1_fs" view.bind="Document" wg-container="Document_form">
    <field name="Question"></field>
  </qp-fieldset>

  <qp-fieldset id="Document_PXLayoutRule2_fs" view.bind="Document" wg-container="Document_form" class="stretch">
    <field name="Answer" control-type="qp-rich-text-editor" class="stretch"></field>
  </qp-fieldset>
</template>

export class AskQuestionFilter extends PXView {
  Question: PXFieldState;
  Answer: PXFieldState;
}

The class stretch on the fieldset makes the grey container area large but doesn’t affect the RichText control. If I add it to both the fieldset and the field then the RichText control stays small (in height), but centers itself vertically in the grey container control, which is even worse.