Use a dedicated directory and preserve the relative relationship between HTML, CSS, JavaScript, images and data. Renaming or moving only one part of the structure is a common cause of broken pages.
Test before customizing
Open the unmodified copy first. Confirm the main page, navigation, styling and key interactive controls work before you add personal CSS or scripts.
Practical check
Keep the process small and testable. Make one meaningful change at a time, confirm the result, and preserve enough context to undo it if needed.
Understand file mode limits
Direct file:// opening can work for simple static assets, but browser security rules can restrict some loading patterns. If a specific version expects local hosting, follow its documented deployment approach rather than trying to bypass browser safeguards.
What to avoid
Avoid mixing advice from unrelated builds as if every copy behaves identically. Version, file structure, enabled data and hosting method can all change the correct next step.
Back up and update safely
Keep a dated archive of the last working setup. Test an update in a separate folder, compare your custom changes, and only switch once the replacement behaves correctly.
Summary checklist
- Work from a clear reference goal.
- Keep source and version context visible.
- Preserve a known-good local backup.
- Test paths and browser behavior before making broad changes.
For a wider overview, return to the 5etools features section or open the complete guide library.