feat: Improved table of contents (#1223)

* feat: New table of contents

* fix: Hide TOC in edit mode

* feat: Highlight follows scroll position

* scroll tracking

* UI

* fix: Unrelated css fix with long doc titles

* Improve responsiveness

* feat: Add keyboard shortcut access to TOC

* fix: Headings should reflect content correctly when viewing old document revision

* flow

* fix: Persist TOC choice between sessions

shared/styles/theme.js

@@ -53,6 +53,13 @@ export const base = {
   selected: colors.primary,
   buttonBackground: colors.primary,
   buttonText: colors.white,
+
+  breakpoints: {
+    mobile: 0, // targeting all devices
+    tablet: 737, // targeting devices that are larger than the iPhone 6 Plus (which is 736px in landscape mode)
+    desktop: 1025, // targeting devices that are larger than the iPad (which is 1024px in landscape mode)
+    desktopLarge: 1550,
+  },
 };
 
 export const light = {