Why would chrome subtract a bit less than .1px from the width of a border?

Question

In chrome dev tools, I'm seeing (in computed styles):

border-bottom-width: 0.9090908765792847px;
  element.style - 1px
  .x-fieldset - 1px
  fieldset, img - 0px
  fieldset - 2px user agent stylesheet

This is on a fieldset element for which the bottom border is not displaying. Very slight perturbations cause this '0.9' to turn to 1, and the border to appear.

All the lines after 'element.style' are struck-through. All this comes from ExtJS, but I have so far failed to see any way to blame it on them.

Answer 1

This is the result of using the chrome zoom feature. If you zoom in chrome, it is implemented by multiplying a factor into the css. and, in some cases, it wipes out borders.