Snackbar container block portion of UI while present.

[dougwollison]

Describe the bug
When a snackbar notice appears, such as after saving changes to a post, the container for it spans the width of the editor UI, including the sidebar. This causes an annoyance where any UI elements at the same Y axis as the snackbar are unclickable, making the user think something is broken when in fact there clicks are being intercepted by an invisible container.

To reproduce
Steps to reproduce the behavior:

1. Open a post/page, with your window sized in a way that there are interactive sidebar elements visible at the bottom of your viewport.
2. Click save/update, the update snackbar notice should appear.
3. Try clicking on said interactive elements, the click will be blocked.

Expected behavior
Since visually the notice is only on a fraction of the width of the screen, clicking those elements while it's present should be possible.

Screenshots
https://imgur.com/wyrbpzY

Suggested Solution
I'm currently patching it by adding this styling to my theme's block editor stylesheet:

.components-editor-notices__snackbar {
	visibility: hidden;

	.components-snackbar {
		visibility: visible;
	}
}

This does the trick, hiding the hitbox of the container while maintaining the hitbox of the actual notice elment.

[talldan]

Thanks for reporting @dougwollison, I can also reproduce that. The visible part of the snackbar also seems very wide now.

[jorgefilipecosta]

In 5.3 the snackbar also seems wide according to the inspector, but the bug did not happen while in 5.4 RC I'm able to reproduce this consistently.