uppy/packages/@uppy/drop-target/src/style.scss

@import '@uppy/core/src/_variables.scss';

.uppy-is-drag-over:after {
  content: '';
  position: fixed;
  top: 7px;
  right: 7px;
  bottom: 7px;
  left: 7px;
  border: 5px dashed $gray-400;
  // border-radius: 5px;
  z-index: 10000;
  background-color: rgba($gray-200, 0.5);
}