1. XML Schema by Priscilla Walmsley - https://www.amazon.com/Definitive-XML-Schema-Priscilla-Walms...
2. DOM Scripting by Jeremy Keith - https://www.amazon.com/DOM-Scripting-Design-JavaScript-Docum...
3. CSS Pocket Reference - Eric Meyer - https://www.amazon.com/CSS-Pocket-Reference-Visual-Presentat...
Most of the developers I have worked with in my career are absolutely terrified by tree structures. They will admit otherwise like some kind of pathological liar, but this is easily exposed and that's so unfortunate. A tree structure is just a data structure like any other and embracing that liberates you from a kind of Stockholm Syndrome.
Not a book but I learned what not to do and what to avoid in my earliest days of programming from the super opinionated tool JSLint.
This was my go to reference to learn CSS https://www.amazon.com/CSS-Pocket-Reference-Visual-Presentat...
As for language design I am mostly self taught through a lot of trial and error. For me it’s all about functions and variable scope. After that everything else is just a statement, expression or a data structure. With that I can write just about anything, make it scale, and keep it super simple to read.