The close button on the sign up banner when visiting a site that you're not a part of is too difficult to see, not only does the low contrast make it harder to see, but it's also near other "shapes" (pluses, triangles, dots, circles) of a similar colour, which causes it to blend in somewhat contextually as well:
This becomes even more apparent when viewing a site on a larger screen:
Can we bump up the contrast to make it easier to see? And potentially move it upwards a bit so that it comfortably sits slightly further away from the other content?