How I Stopped UI State Drift with a DOM Boundary Approach

One of the most frustrating UI failures is not a dramatic JavaScript bug. It is when CSS stops feeling explainable. You change one screen and another screen shifts. The same HTML looks different depending on where it appears. After a while, it becomes difficult to tell which style is actually responsible for what you are seeing. The Real Problem Was Separation At first, this looks like a CSS problem. In practice, it is usually a structure problem. HTML defines the shape of the UI. CSS often lives somewhere else entirely. DOM behavior is then added from another place again. Each part may look reasonable on its own, but the unit they are supposed to describe no longer exists in one place. That is where drift starts. The UI is assembled from related parts that are managed as if they were unrelated. When a UI Unit Does Not Exist This was the point that kept bothering me in real screens. HTML alone does not fully describe the element as it actually behaves. CSS alone does not tell you which