There are several challenges due to the complexity of animation and functionality of site. The most notable challenge I overcome is making a contact form from scratch that validates user inputs, links to the database, auto-replies to the sender and send the message to a customizable destination. The form uses the combination of HTML and PHP to present the front-end interface while setting variables for submitting the data using POST method. The code can break with even a minor mistake such as missing a semi-colon at the end.
The second problem I encounter is adopting new framework and plug-in. Materialized is very similar to other CSS frameworks such as Bootstrap and Pure that I have worked with before. ScrollMagic however is a bit more difficult to learn, especially to tweak pre-built components and make it mobile responsive. Pre-production preparation is as time consuming. After determining to use 7 images to form the scroll animation, I first draw them on Illustrator and adjust movement using Puppet tool only to realize that it does not deliver the doodling feel that I like. I end up have to draw it by hand and tune the image with Photoshop.