Add 'flex-base: auto' for RadioButtonCircle

* This allows the circle to adjust the size automatically and works with both box-sizing models

src/components/RadioButton/index.tsx

@@ -86,7 +86,7 @@ const RadioButtonCircle = styled.div(
   vertical-align: middle;
   position: relative;
   overflow: hidden;
-  flex: 0 0 0.5em;
+  flex: 0 0 auto;
   padding: 0.1875em;
   border: 2px solid ${ui5};
   border-radius: 100%;