Remove webkit button shadow

So far I am not aware of any box shadow added to buttons by default in Webkit. Are you sure that this comes from webkit and not your theme?

The styles of Lightbox with Photobox already include removing box shadows, but this only works if the theme or other plugins don’t overwrite the global button rule (which is very bad anyway and not only a problem for Lightbox with Photoswipe):

.pswp__button {
  width: 44px;
  height: 44px;
  position: relative;
  background-color: #00000000 !important;
  cursor: pointer;
  overflow: visible;
  -webkit-appearance: none;
  display: block;
  border: 0;
  padding: 0;
  margin: 0;
  float: right;
  opacity: 0.75;
  -webkit-transition: opacity 0.2s;
          transition: opacity 0.2s;
  -webkit-box-shadow: none;
          box-shadow: none;
  min-width: 0;  }

So if you still have box shadows, then your theme or any of the other plugins must have some global style like this:

button {
  box-shadow: ...
}

Anyway – I will add some rules to make sure that the buttons will be display properly even if a another theme or plugin has too lazy rules which will affect everything else as well and not only its own elements.