Also wondering how the structure switched back to floating when flexbox was selected? after the new update
That’s super strange. I haven’t been able to replicate this and we haven’t received other reports currently. GP Premium should not change that option at all as it’s a theme option.
We will take a closer look if we receive more reports on this.
As for the border question, edit Elvin’s CSS to this instead:
.sidebar .widget_text {
border: 3px solid #572794;
}