Background - base layer shows through

Not sure how you size and place your slide layers, but one thing you could do so base layer won't show through:

Slide layer (right click) -> Properties -> Visibility -> Hide objects on the base layer.

It might lead to some white space popping up on the left in the preview and publish. I'd also purpose you to enlarge the background image of the slide layer, so that its edges are slightly over the canvas. Doing so, no matter it shrinks or not, it would cover the entire screen.

Based on the image, it looks like you have a filled rectangle as the background object on the layer (or possibly on the Feedback Master Layout applied to that layer). And that rectangle isn't covering the entire slide. For example, the rectangle might be somewhat narrower than the slide and aligned on the right. Or it might be the same width as the slide, but moved slightly to the right. If either of those is the case, that's why a small strip of the base is showing through on the left. The solution is to adjust the size and/or placement of the rectangle.

If that's not the case, well, troubleshooting is just guessing without seeing the .story file. If you upload it, someone might be able to solve the issue. Here are the best practices for doing that:

• Only include slides that are related to the problem.
• Be sure objects, layers, motion paths, and variables have meaningful names.
• If there is proprietary content, replace or delete it. For example, replace proprietary text with “ipsum lorem” text.

If it is just a coloured background I would remove and set the background property to that colour

Thank you Judy! I will look into these possibilities. Sorry for the delayed response. Life has been busy outside of SL these days.