fix(theme): don't reset scroll position on changing tab in code groups

closes #2732, closes #2362

Author: brc-dd

Diff for: src/client/theme-default/styles/components/vp-code-group.css

@@ -23,7 +23,7 @@
 }
 
 .vp-code-group .tabs input {
-  position: absolute;
+  position: fixed;
   opacity: 0;
   pointer-events: none;
 }