Even on the Desktop Web Browser (where I was), by default the scrollbars are hidden (macOS). It is not apparent that the content is scrollable but confined in a frame/container. I had to stumble on it when I graze over the Magic Mouse because the cursor is outside of the content (inside the frame/container).

Contents inside a frame is OK but make it apparent, say, have a thin border, with a lightly different backgound and have the scrollbar forced if the content is larger than the defined height of the frame.