Indeed, zooming in and out reproduces the bug. Also, refreshing the page without doing any zooming on the page shows a different button size compared to Chrome. I was confused by the original STRs: "See testcase, when clicking on the button, it shrinks, which is usually our to-go STRs. But will take that into consideration for future references. Thanks for the heads-up.
Bug 385615 Comment 55 Edit History
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Indeed, zooming in and out reproduces the bug. Also, refreshing the page without doing any zooming on the page shows a different button size compared to Chrome. I was confused by the original STRs: "See testcase, when clicking on the button, it shrinks", which is usually our to-go STRs. But will take that into consideration for future references. Thanks for the heads-up.