Math, algorithms and data strctures are not really the critical thing to learn for web development. Hopefully your grads are not starting out architecting anything complicated but instead following best practices and good workflow and leaving the majority of the algorithm architecting to people with much more experience and training.
The important thing to teach are the best practices in web component composition and workflow. These are also rapidly changing, with many competiting tools, but in a consistent direction: modular, testable components as services on top of robust development infrastructure including source control (git), code reviews, continuous integration, rapid, numerous deploys wth no downtime etc. There are lot of good resources about this, but the key thing is to see it in practice, to get hooked on how good workflow and a focus on code quality can make your work a joy instead of a nightmare. There is a huge amount to learn about the latest web development processes, but students (like yours) should be helped to paddle out and get on top of the wave so they can keep riding it - not be taught liquid mechanics or how to build a surfboard.
My dream web dev class would have one website that is built many ways but with similar workflow and final result. Rails stack, python stack, php stack, node stack, etc all using the same assets. Enough versions of the same site that all the students can work in groups to implement the same thing on each stack. Teach what is the same between the stacks (e.g. MVC), without the details of the stack's implementation of that concept and you'll be teaching a lesson that they can carry with them for a long time. Although that might be too difficult for people who haven't done any programming ever, but I think I'd enjoy that class. Regardless, you should have some code that implements a real website with real workflow that they can learn from.