diff -r d4ec02c51c91 -r af15590802a4 assets/stylesheets/bootstrap/mixins/_size.scss
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/assets/stylesheets/bootstrap/mixins/_size.scss	Thu Jun 15 12:17:09 2017 +0200
@@ -0,0 +1,10 @@
+// Sizing shortcuts
+
+@mixin size($width, $height) {
+  width: $width;
+  height: $height;
+}
+
+@mixin square($size) {
+  @include size($size, $size);
+}