Layout of visible scrollbars, to be precise scrollbars that take space off scrollable, may oscillate - not always has a determined solution in case of `overflow:auto;`, steps:
1. You start layout width without any scrollbars to determine height of the content;
2. If content height exceeds height of the scrollable you will need to show v-scrollbar, and so goto #1;
3. While reducing available width at #2 you may have content width overflow width of scrollable container minus v-scrollbar, so you need to show h-scrollbar that reduces available height, and so goto #2;
There are conditions at particular content/container sizes and layout algorithms when the solution oscillates.
So `overflow:auto;` (show scrollbars only when needed) is a) quite expensive (layout happens multiple times) and b) not that easy to implement.
Floating scrollbars that appear on top of scrollable content and so do not take screen space are technically better.
Layout of visible scrollbars, to be precise scrollbars that take space off scrollable, may oscillate - not always has a determined solution in case of `overflow:auto;`, steps:
1. You start layout width without any scrollbars to determine height of the content;
2. If content height exceeds height of the scrollable you will need to show v-scrollbar, and so goto #1;
3. While reducing available width at #2 you may have content width overflow width of scrollable container minus v-scrollbar, so you need to show h-scrollbar that reduces available height, and so goto #2;
There are conditions at particular content/container sizes and layout algorithms when the solution oscillates.
So `overflow:auto;` (show scrollbars only when needed) is a) quite expensive (layout happens multiple times) and b) not that easy to implement.
Floating scrollbars that appear on top of scrollable content and so do not take screen space are technically better.