box-sizing

src/scss/_common.scss

@@ -2,11 +2,14 @@
 * General Uppy styles that apply to everything inside the .Uppy container
 */
 
-.Uppy,
-.Uppy * {
+.Uppy {
   box-sizing: border-box;
 }
 
+.Uppy *, .Uppy *:before, .Uppy *:after {
+  box-sizing: inherit;
+}
+
 .UppyIcon {
   max-width: 100%;
   max-height: 100%;