sets border-radius when vertical buttons have a single child button

src/definitions/elements/button.less

@@ -3409,24 +3409,16 @@
   width: 100%;
   margin: @verticalGroupOffset;
   box-shadow: @verticalBoxShadow;
+  border-radius: 0em;
+}
+.ui.vertical.buttons .button:first-child {
+  border-top-left-radius: @borderRadius;
+  border-top-right-radius: @borderRadius;
 }
-.ui.vertical.buttons .button:first-child,
-.ui.vertical.buttons .mini.button:first-child,
-.ui.vertical.buttons .tiny.button:first-child,
-.ui.vertical.buttons .small.button:first-child,
-.ui.vertical.buttons .massive.button:first-child,
-.ui.vertical.buttons .huge.button:first-child {
-  border-radius: @borderRadius @borderRadius 0px 0px;
-}
-.ui.vertical.buttons .button:last-child,
-.ui.vertical.buttons .mini.button:last-child,
-.ui.vertical.buttons .tiny.button:last-child,
-.ui.vertical.buttons .small.button:last-child,
-.ui.vertical.buttons .massive.button:last-child,
-.ui.vertical.buttons .huge.button:last-child,
-.ui.vertical.buttons .gigantic.button:last-child {
+.ui.vertical.buttons .button:last-child {
   margin-bottom: 0px;
-  border-radius: 0px 0px @borderRadius @borderRadius;
+  border-bottom-left-radius: @borderRadius;
+  border-bottom-right-radius: @borderRadius;
 }
 
 .loadUIOverrides();