Shimmer marks live status text without changing its content. Its root always
has sui-shimmer; animation and gradient styling apply only while active.
Reduced-motion environments render readable muted text with no animation.
active defaults to true. Set it to false to retain ordinary inherited
text styling.
The same chatScrollerCss block ships .sui-scroll-fade. Apply it to a
scrollable element with data-fade-top="true|false" and
data-fade-bottom="true|false"; MessageScroller manages those attributes
automatically.