Todo App using Sass and Vanilla Javascript

Hello everyone! I've just finished this intermediate challenge and it's really fun to make this app. I've learned new things and can practice my new knowledge about SASS. In order to improve my skills and code, I want to ask few things :

1. If I add todo with long character without any space which is just one word, the todo item will be overflow and doesn't expand or make a new line. How to deal with that? Is it only working with Javascript or we can make it with css?
2. I wonder what is the best workflow for styling the layout, could you make the steps for me? like is it wil be try to make the variables first or reset the css?
3. And how to organize the code in order to make the code look clean and maintanable for Javascript and SASS/CSS

Thanks in advance