Under the Hood: Drag, Touch, and CSS Cascade in a Real Diff UI

Short summary

When building responsive drag-and-drop UI, read CSS state with getComputedStyle() instead of hardcoded breakpoints, unify touch/mouse events with optional chaining on the touches array, and attach listeners to document to track mid-drag pointer drift. Use two-class CSS selectors to prevent visibility rules from colliding with layout classes. A practical reference for flex-basis, event coordinates, and the CSS cascade.

• •Use getComputedStyle() to read resolved layout state instead of hardcoded window.innerWidth breakpoints
• •Unify touch and mouse events with e.touches?.[0] ?? e and attach listeners to document, not just the draggable element
• •Fix CSS specificity conflicts in visibility systems by using two-class selectors to prevent display rules from overriding layout classes

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