Refactor sidebar (#6971)

* Refactor RightNav

(cherry picked from commit 96bb02acfd2d7452df18a0e7410e6a7169a583ed)

* Better gutter handling

* Clean up styles

* Memoize breakpoints

* Format

* Comment

* Loosen spacing, handle overflow, smaller text to match prod

* Fix circular imports on native

* Return 0 instead of undefined for easier calculations

* Re-assign

* Fix

* Port over fix from subs/base

* Space out right nav feeds, widen sidebar to match prod

* Fix lost padding on home header

* Fix perf by not actually linking to new URL

* Remove underline on focus

* Foramt

---------

Co-authored-by: Dan Abramov <dan.abramov@gmail.com>

src/alf/breakpoints.ts

@@ -0,0 +1,28 @@
+import {useMemo} from 'react'
+import {useMediaQuery} from 'react-responsive'
+
+export type Breakpoint = 'gtPhone' | 'gtMobile' | 'gtTablet'
+
+export function useBreakpoints(): Record<Breakpoint, boolean> & {
+  activeBreakpoint: Breakpoint | undefined
+} {
+  const gtPhone = useMediaQuery({minWidth: 500})
+  const gtMobile = useMediaQuery({minWidth: 800})
+  const gtTablet = useMediaQuery({minWidth: 1300})
+  return useMemo(() => {
+    let active: Breakpoint | undefined
+    if (gtTablet) {
+      active = 'gtTablet'
+    } else if (gtMobile) {
+      active = 'gtMobile'
+    } else if (gtPhone) {
+      active = 'gtPhone'
+    }
+    return {
+      activeBreakpoint: active,
+      gtPhone,
+      gtMobile,
+      gtTablet,
+    }
+  }, [gtPhone, gtMobile, gtTablet])
+}