01 · My idea

I wanted to create a website where someone could enter their date of birth and discover their age, zodiac sign, time until their next birthday, historical events and people who share their birthday.

I also wanted the experience to feel personal, with a greeting, background music and a ready-to-send WhatsApp message.

02 · How I used ChatGPT

I used ChatGPT to help plan and generate the HTML, CSS and JavaScript. I described the features I wanted and requested changes as the project developed.

The first version needed an internet connection to look up historical events and birthdays. After noticing this, I asked ChatGPT to create a local data file containing a selection of records going back about 200 years.

ChatGPT assisted with code generation, data extraction, debugging and checks. The historical information comes from English Wikipedia contributors, whose sources and licence are credited in the project.

03 · How the files work together

• HTML creates the form, result cards, tabs and audio player.
• CSS controls the colours, spacing and layout on different screen sizes.
• JavaScript calculates age and the countdown, displays local records and prepares the WhatsApp link.
• dados.js stores the history and birthday collection for all 366 calendar dates.
• The local MP3 provides the background music without streaming. The music was done with Suno AI. Suno is the other AI I used.

04 · Challenges and solutions

• Internet-dependent information: the records were collected into a local file.
• Dates and leap years: the calculator rejects invalid dates and uses February 28 for leap-day birthdays in non-leap years.
• Large lists: search and “Show more” buttons make the records easier to explore.
• Automatic music: some browsers block sound until a user interacts. The page tries autoplay, then offers a Play button and starts after an interaction when allowed.
• WhatsApp: the page prepares a message, but the user reviews and sends it.

05 · Why “Offline edition”?

The calculations, zodiac descriptions, history, birthday records and music are stored with the website. Once the folder is downloaded and extracted, the main features work without an internet connection.

A hosted page still needs a connection to download its files. WhatsApp and external source links also need internet. “Offline edition” refers to the local application and its bundled content, not to those external services.

06 · What I learned and checked

This project helped me understand how a webpage uses data, how HTML, CSS and JavaScript work together, and how an online lookup differs from a local dataset.

The code was checked for age calculations, invalid dates, leap years, countdowns, international phone formatting and personalised WhatsApp links. The data was checked for coverage of all 366 dates and the selected year range.

The historical records are a selection, not a complete history of the world. They were not independently fact-checked against every original reference. Astrology descriptions are included as entertainment.