When it comes to practical guides, I HIGHLY recommend the book RefactoringUI by Steve Schoger!(creator of TailwindCSS.)

Unlike popular books in design that people talk about like "The Design of Everyday Things" or "Don't Make Me Think"(which teach design from a perspective of usability and human psychology, very important as well), RefactoringUI goes into the actual implementations of design.

For example, he talks about how he thinks about padding in elements, shadows vs borders, rounded corners, choosing font sizes/font colors and etc.(It's rare to find books to be *this practical because web design is constantly changing and it's hard to not be outdated)

I also recommend designcode.io courses. They are also extremely practical, even going into things like keyboard shortcuts on Figma, plugins you can use to Skew elements, etc.

Both resources are known to be a "developer's guide to design", which I think you may appreciate!

That being said, making a website look "nice" is only the frosting on the cake! Don't over-optimize on the looks and neglect the filling.

read this: https://www.amazon.com/Dont-Make-Me-Think-Usability/dp/03213...

and this: https://www.amazon.com/Big-Red-Fez-Make-Better/dp/0743227905

that's really all you need.

I am a developer and I used to struggle a lot creating a good looking websites. What helped me pretty well is using platforms like Dribbble to take inspirations.

On Dribbble you can search for the specific kind of UI that you want to built, for e.g. Admin Dashboard, Login Page, Splash Screen etc and you will start seeing so many good designs in front you.

Once you have that set, you can shortlist 3-4 designs and take inspirations from them. You should also mention the designer in the project rom whom you took inspiration. I mostly used to do this for my side projects.

May not be a very good way to do things, but atleast it will help you get started.