📚 Intermediate: Contents (3/8)
  1. Build your first web page with Codex
  2. How folders, files, and HTML fit together
  3. Change an existing page the way you want
  4. Read errors and fix them with Codex
  5. Connect Google Drive and search your first doc
  6. Connect GitHub and choose repository access
  7. Connect Notion and check which pages it can see
  8. Connect Slack and summarize a channel

🔁 Cuts repetitive work

New to AI? Start here → Start 1. ChatGPT vs. Codex: what's the difference?

Last checked: November 10, 2026

Change an existing page the way you want

In one line

Change an existing page the way you want
Instead of changing everything at once, fix one thing at a time and check as you go.

The big picture

Illustration (may look a little different from the real screen)

Change the title and colors, keep the book list
Click the picture to see it larger.

Follow along

Keep a copy of how it was before

We’ll use the reading-log example. First copy the folder somewhere safe, or save the current state with whatever version control you use. Copying the files doesn’t back up data saved in the browser.

Separate what to change from what to keep

Instead of “Make it look nice,” say where on the page and what change you want. Saying what should stay the same, so saving and data don’t change too, makes it easier to review.

After a design change, check three times

1. Check which files the plan changes

First have it explain the related files and how much it will change. If it wants to rebuild the whole structure just to change one color, ask again with a narrower scope.

2. Refresh the same file

After Codex saves the file, refresh the browser you had open. If nothing changed, check that the file it changed is the same one open in your browser.

3. Click through the existing features again

Check in order: add a book → mark as read → refresh → delete. Also make the browser window narrower and check that text and buttons don’t overlap.

Prompts you can copy

Change only part of the page

Make only the following changes to the current reading-log page. Change: the title to My Reading Notes, the accent color to blue, and wider spacing between buttons on mobile. Keep: adding, marking as read, and deleting books, plus the existing storage key and data format. First explain the related files and your plan. After the change, tell me what you changed, what you checked, and the steps for me to check it myself.

Undo a change you didn’t want

From the change you just made, I want to undo only [the change I didn't want]. Keep [the change I want to keep]. First look at the current changes and explain which part of which file you'll undo. Don't delete existing data or unrelated files.

Where people get stuck

Lots of people get stuck here. Find the one that matches your situation!

Compare before and after

Illustration (may look a little different from the real screen)

Narrow the browser to check the mobile layout too
Click the picture to see it larger.

If something changed that you didn’t expect, ask for the changed files and what changed. When going back to an older file, make sure it doesn’t wipe out later changes too.

Quick check: After changing the colors, do I still need to check adding and saving books?

Answer: “Yes, check the existing features too”
Even design changes can affect how things work. Check the main flow again.

Official sources

Next tip

Read errors and fix them with Codex →

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