Writing parsers honestly isn't that hard, especially when you have more or less step-by-step instructions for some of the formats, and test suites that independent 3rd parties have written that you can use to help verify your implementation.
Regardless, so what if it's "bad"? OP is using this as a learning experience too. If he wants to write parsers, and thinks that experience will be good for him, then he should write parsers.
I do agree that writing your own parsers isn't strictly necessary if you want to write an independent web renderer/browser. If I were tackling this project, I'd be more interested in and curious about how to write a renderer, and if there's a HTML or CSS parsing crate already written and available on crates.io, I'd probably use it.
Then again, writing a parser would also make me intimately familiar with HTML and CSS in ways that I'm probably not currently, and that might help inform how I build the renderer.
Regardless, so what if it's "bad"? OP is using this as a learning experience too. If he wants to write parsers, and thinks that experience will be good for him, then he should write parsers.
I do agree that writing your own parsers isn't strictly necessary if you want to write an independent web renderer/browser. If I were tackling this project, I'd be more interested in and curious about how to write a renderer, and if there's a HTML or CSS parsing crate already written and available on crates.io, I'd probably use it.
Then again, writing a parser would also make me intimately familiar with HTML and CSS in ways that I'm probably not currently, and that might help inform how I build the renderer.