White around the image when the mouse is over

For example, the "Back to Top" button, as in the example,

When you mouse over,

As you can see, the surroundings of the image become white and a little ugly. Is there a way to make it white when I mouse over it?

The top button is not created with CSS, but with an image (translucent png). By the way, this phenomenon does not occur when creating only with CSS. However, the position of the upward arrow in the inside slightly changes depending on the browser, so it is not good enough, so it is png (although CSS may be poorly written ...)

Environment is macOS 10.13.3, and the browser that can confirm the symptom is chrome version: 68.0.3440.106 (Official Build) (64 bit), fireFOX 61.0.1 (64 bit), opera, 55.0.2994.37. safari could not be reproduced.

Thanks for your patience. Thank you.

  • Answer # 1

    Sorry for the late response. I solved it myself.

    The background color applied to a: hover was white. Thank you very much.