Sorry, Sharmila, your reply got marked as spam for some reason and was hidden. It’s visible now.
The individual dimensions of images will have to be set in each image. You can use style= within the img tag to add style, or width and height properties. But those are enclosed in the img tag, not in a style sheet. See the examples from W3C Schools on the image tag for examples.
https://www.w3schools.com/tags/tag_img.asp
You jumped ahead a bit in the course; I explained how to add images in the week 7 live session. Maybe it will make more sense after you watch that.
Sugarcube does have more options for programming than Harlowe, partly because it’s designed to work more efficiently with Javascript. You are welcome to switch your story style to Sugarcube, but understand that I won’t be able to support you anymore. You’ll be on your own to find the resources online or to use the Twine Discord community for help.
Sugarcube is designed for people who already know web programming, CSS, and Javascript, so many game designers prefer it because they have those existing skills. Harlowe is designed for people who don’t already have those programming skills, which is why that’s what I use and what I teach in this course. If you feel like your existing CSS and Javascript skills are up to it, you absolutely can do more complex development beyond the scope of this course.
I don’t recommend using a timer as a feedback. I explain why in this blog post. (There are times when I think it’s helpful, but this isn’t one of them.) https://www.christytuckerlearning.com/using-time-as-scenario-feedback/
If you want to add one anyway, there’s a suggestion here that you can try.
https://twinery.org/forum/discussion/5508/countdown-timer-harlowe
Don’t forget to change the image paths for your images to relative images and to keep everything in a folder together. I do see the html file, but of course I only see the alt text for the images currently since the links are all broken and I don’t have the image files. That’s fine for this review, but for the week 7 assignment you’ll need it all together.