stereokai

.rounded-corners-gradient-borders {
  width: 300px;
  height: 80px;
  border: double 4px transparent;
  border-radius: 80px;
  background-image: linear-gradient(white, white), radial-gradient(circle at top left, #f00,#3020ff);
  background-origin: border-box;
  background-clip: padding-box, border-box;
}

codler

/*! Prefix flex for IE10 and Safari / iOS in LESS
* https://gist.github.com/codler/2148ba4ff096a19f08ea
* Copyright (c) 2014 Han Lin Yap http://yap.nu; MIT license */

.display(@value) when (@value = flex) {
	display: -ms-flexbox; // IE10
	display: -webkit-flex; // Safari / iOS
}

.display(@value) when (@value = inline-flex) {