73bc270bc gave :host a height and stopped the ELEMENT overflowing. It did not
stop the MAP, because it never made the host a containing block.
.gm is position:absolute;inset:0, which resolves against the nearest POSITIONED
ancestor. :host had display:block and a height but no position, so on a partner
page .gm resolved against whatever the PARTNER had positioned and the map sized
itself to that. rega measured it in the hostbox run on ca07fc3c8: the element
correct at 420px inside a 420px box, the canvas inside it still 900px, and the
"Tap a coloured dot" pill and the attribution painting 478px below the box —
538px in a 360px box — over the partner's own text, whose top sits at y=464/404.
position:relative on :host is the whole fix, and it is the house pattern:
prayer-walk-planner.vue:628 carries the identical shape with an absolute child.
Worth recording, because the first fix passed every check: a host box that is
the right size proves nothing about what is drawn inside it. Only a partner-page
shot with content BELOW the box can see this, which is why rega's hostbox run
found it and my source reading did not.
60cb4ff184