Splitpanes is a Vue.js library that enables pane splitting and resizing, as shown below.
https://github.com/antoniandre/splitpanes
When using this library, I encountered an issue where resizing did not work properly when a pane contained an iframe element. A solution was described in the following pull request.
https://github.com/antoniandre/splitpanes/pull/162
As described there, adding the following CSS resolved the issue and allowed correct resize operations even with panes containing iframe elements.
I hope this helps anyone experiencing the same issue.