The chart card and its outer widget shell both had overflow:visible,
letting chart lines bleed past their rounded borders into neighboring
widgets. Compact-mode charts also stretched to fill the widget's full
resized height instead of staying compact like other widgets.
Additionally, the history used to build the chart needs 2+ points to
render a line - it started empty and only got its first real point on
the next poll (up to 30s later), so the chart would flash between a
single-value fallback and the actual graph. Both the initial render
and the first state update now seed with the current value duplicated,
so a flat line renders immediately with no flicker.
Bergasha
ajnart