Add the unprefixed appearance property.

XhmikosR · XhmikosR · commit 627b35954137 · 2018-11-18T10:00:03.000+02:00
diff --git a/less/close.less b/less/close.less
@@ -32,5 +32,6 @@
     background: transparent;
     border: 0;
     -webkit-appearance: none;
+    appearance: none;
   }
 }
diff --git a/less/forms.less b/less/forms.less
@@ -56,6 +56,7 @@ input[type="search"] {
   // be added to `.form-control` as it's not specific enough. For details, see
   // https://github.com/twbs/bootstrap/issues/11586.
   -webkit-appearance: none;
+  appearance: none;
 }
 
 // Position radios and checkboxes better

Original file line number	Diff line number	Diff line change
`@@ -56,6 +56,7 @@ input[type="search"] {`
`56`	`56`	// be added to `.form-control` as it's not specific enough. For details, see
`57`	`57`	`// https://github.com/twbs/bootstrap/issues/11586.`
`58`	`58`	`-webkit-appearance: none;`
	`59`	`+ appearance: none;`
`59`	`60`	`}`
`60`	`61`
`61`	`62`	`// Position radios and checkboxes better`