If you have created an image that extends beyond the width of your content, on all browsers a scrollbar will now appear.
|Ugly Ugly, Get Rid of It|
Now I made all my images width set to 30 pixels minus the Site Width set in Manage Site > Site Layout. Most of my pages are 940 pixels wide, so I had images set to 910 pixels. Through some update to Google Sites this causes a scrollbar to appear.
The most efficient solution, rather than change the width of your images in the HTML, is to change your Site Width. Now all my images must be 32 pixels minus the Site Width in order to avoid the scrollbar.
Alternative is the edit HTML, and in the <img src="..."> add width="[## SITE WIDTH - 32 PIXELS]px"
Unannounced updates and unforeseen bugs from the Google Sites team really throw me for a loop. I'll try to keep all up to date with any Google Sites bugs that come our way. Quickly look over your designs today or this week and make sure there are no gaudy scrollbars.