html, css with scss and javascript

Tasks are added with the enter key. When creating the dark mode, the checkbox was complicated by being active in changing the color of each task and removing the effect of the complete tasks. I think they were done with the same event that adds the tasks with the enter key, I tried to do it by adding classes, but when doing it I changed them in clear mode. In the same way in the rounded borders in only applying it to the first element, I did not find a way to do it.