Earlier quoted context omitted.
A splitter is the widget that shows two (or more) panes with a divider that you can drag. Commonly used for side bar navigation, see this example: https://codepen.io/Zodiase/pen/qmjyKL A native splitter is one that is drawn by the browser itself, or even the OS. The only way to get that on the web is with iframes. Otherwise you have to resort to Javascript and manually handling mouse move events as in the example abo…
I believe you mean / rather than s, though you used to be able to do frames inside iframes. I’m surprised mobile Safari supports them. Example: https://www.quackit.com/html/templates/frames/frames_example...
Your example has `noresize` set, but I found one that doesn't: https://www.yourhtmlsource.com/examples/frameset1.html