Improve 404 navigation and styling

src-ui/src/app/components/document-list/document-list.component.spec.ts

@@ -259,7 +259,7 @@ describe('DocumentListComponent', () => {
       .mockReturnValue(of(convertToParamMap({ id: '10' })))
     const navigateSpy = jest.spyOn(router, 'navigate')
     fixture.detectChanges()
-    expect(navigateSpy).toHaveBeenCalledWith(['404'])
+    expect(navigateSpy).toHaveBeenCalledWith(['404'], { replaceUrl: true })
   })
 
   it('should load saved view from query params', () => {

src-ui/src/app/components/document-list/document-list.component.ts

@@ -153,7 +153,9 @@ export class DocumentListComponent
       .pipe(takeUntil(this.unsubscribeNotifier))
       .subscribe(({ view }) => {
         if (!view) {
-          this.router.navigate(['404'])
+          this.router.navigate(['404'], {
+            replaceUrl: true,
+          })
           return
         }
         this.unmodifiedSavedView = view