I discovered that the problem was a result of the Windows display settings.  In the system settings 'display' menu there is 'Scale' option for which the default and recommended setting is 125%, which will 'change the size of text, apps, and other items'. When I changed the scale setting to 100% this resolves the strip background image zooming issue I was encountering as shown above.

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HOWEVER, this still concerns me because with 125% being the default and recommended value for the display scale setting, this means a potentially large percentage of my website visitors using Windows will be encountering this issue. And because the issue only occurs on the live site and not in preview mode (at 125% scale settings), I'm hoping that there is a way to fix this issue so that my website will be displayed correctly regardless of the visitor's Windows display scale settings, as it seems to be possible given that it is displayed correctly in 'Preview Mode' at 125% scale.

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Here are the Windows display 'scale' settings that I'm referring to: