Hi Ben,
Thanks for your response! The embedded timeline is incorporated into our theme and appears on our homepage and every page on our site, you can see it at http://planetpov.com in the right column.
When the page is viewed in IE or Safari, the embedded Twitter widget displays properly but when I view the same page in Firefox (latest version, 33.0) the Follow button is altered, appears as shown in my post and forces the timeline down and out of view.
I am using the standard Twitter widget/embed tool at your site, using the code generated by that tool on my site. That embed code had been working normally for more than a year until this week.
When the widget loads, it displays the timeline for a split second before the header with the too-big Follow button and follower count appears then the time line is shoved down and replaced by blank space.
Hope this is helpful. Appreciate the assistance!