The Upload files tab of New transfer. 1px dashed --border on --app-bg, radius 4. Dragging goes solid on --component-bg-active; the border says accept (green) or reject (red). The copy never changes.

Dragging files anywhere in the app fades in a --component-bg-active layer at 75% with a dashed inner frame. Drop uploads to the default download folder, or the current folder if that setting is on.

Dropped files go to the task dock as one Uploading card, a row per file. Full states live on Tasks. app.put.io draws these icons from its flaticon font.