Dark mode: navbar bg, update snapshots

app/soapbox/components/ui/column/__tests__/__snapshots__/column.test.js.snap

@@ -6,7 +6,7 @@ exports[`<Column /> renders correctly with minimal props 1`] = `
   role="region"
 >
   <div
-    className="space-y-4 bg-white sm:shadow-lg overflow-hidden p-4 sm:rounded-xl"
+    className="space-y-4 bg-white dark:bg-slate-800 sm:shadow-lg dark:sm:shadow-inset overflow-hidden p-4 sm:rounded-xl"
   >
     <div
       className="mb-4 flex flex-row items-center"

app/soapbox/features/ui/components/navbar.tsx

@@ -30,7 +30,7 @@ const Navbar = () => {
   const onOpenSidebar = () => dispatch(openSidebar());
 
   return (
-    <nav className='bg-white shadow z-50 sticky top-0' ref={node}>
+    <nav className='bg-white dark:bg-slate-800 shadow z-50 sticky top-0' ref={node}>
       <div className='max-w-7xl mx-auto px-2 sm:px-6 lg:px-8'>
         <div className='relative flex justify-between h-12 lg:h-16'>
           {account && (