add timezone support, tons of CSS and layout improvements, more detailed snapshot admin form info, ability to sort by recently updated, better grid view styling, better table layouts, better dark mode support

archivebox/core/admin.py

@@ -3,6 +3,7 @@ __package__ = 'archivebox.core'
 from io import StringIO
 from pathlib import Path
 from contextlib import redirect_stdout
+from datetime import datetime, timezone
 
 from django.contrib import admin
 from django.urls import path