Move back to height: 100% to size the scroller

Reverts 446e8bb

FIX: Fix an issue where the content and gutters in a fixed-height editor could be
smaller than the editor height.

See https://discuss.codemirror.net/t/safari-not-setting-focus-on-wrapper-scroller-mouse-click/3131

src/theme.ts

@@ -45,7 +45,7 @@ export const baseTheme = buildTheme("." + baseThemeID, {
     alignItems: "flex-start !important",
     fontFamily: "monospace",
     lineHeight: 1.4,
-    flexGrow: 2,
+    height: "100%",
     overflowX: "auto",
     position: "relative",
     zIndex: 0