Vector circles look like hexagons in browser

Animating an HTML 5 banner. It features seven tiny circles that grow in size and turn into icons. As the circles grow out, their edges become jagged, kind of like hexagons. This only seems to happen when I view the animation in a browser after I've published it. In Animate canvas, it looks fine and smooth. It's brief but the client has noticed and commented on it. Does anyone know why it does this? I get the feeling it can't be helped, but if anyone's run into this problem and has a solution, let me know.

Here's the banner in question