Main: fix IE compatibility issues (#12237)

packages/theme-chalk/src/main.scss

@@ -2,6 +2,8 @@
 @import "common/var";
 
 @include b(main) {
+  // IE11 supports the <main> element partially https://caniuse.com/#search=main
+  display: block;
   flex: 1;
   flex-basis: auto;
   overflow: auto;