.sys-detail-loading and .sys-detail-empty are absolutely-positioned overlays
that JS shows/hides via the `hidden` attribute. Their .sys-detail-* rule sets
`display: flex`, an author declaration that overrides the UA
`[hidden] { display: none }` — so `el.hidden = true` never actually hid them.
Both the 'Loading history…' and 'No samples in this range yet' overlays stayed
painted on top of a fully-populated chart (overlapping into garbled text).
Add `.sys-detail-loading[hidden], .sys-detail-empty[hidden] { display: none }`
(higher specificity than the bare class) so the hidden attribute wins.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Signed-off-by: librelad <librelad@digitalangels.vip>