I've worked as a designer/developer at Dealer.com for nearly 10 years. I started here as a Digital Creative Designer, but moved the AdCreative team. I'm now a Sr. Developer and have been able to learn a ton of HTML, CSS, and JS, along with a lot of UI Animation fundamentals. My primary role is the design and development of JS based interactive banner ads, but I also build out landings pages for brands and create custom video ads as well.
Layout and design come into play quite a lot with our ads and landing pages. Typography, color theory, and eye-catching visuals all come into play.
All of our ads are heavily JS focused and then our landing pages are equal parts HTML, CSS, and JS. All ads are customizable and many landing pages need to be as well.
A lot of thought goes into the animations, button effects, and overall interaction with our ads. Some ads can even allow you to scroll through new inventory. This interactive aspect really allows for creativity, along with user engagement and interaction.