{# Small hover-info icon showing a PlotConfig field's Pydantic Field description as a tooltip - used next to Plot Editor labels (_chart.html) so each control's exact semantics (units, valid range, what "None" does, etc.) are one hover away, sourced from the same /mosaic/api/plot-config-schema the JSON editor's own CodeMirror hover tooltips read (trial-viewer.ts's plotFieldHelp/describeSchemaPath), not a hand-written copy that could drift from the actual field. Icon + .tooltip-panel is the same pure-CSS group-hover pattern the X-Axis selector's own help icon already uses (_series_panel.html) - reused here as a macro since this one repeats across every field in the popover rather than being written out once. help_expr is an Alpine expression string (not a literal value, same convention as this file's other macros) - typically "plotFieldHelp('someKey')". x-show hides the icon until the schema's loaded (a fetch on page init, not instant) rather than showing a dead icon with an empty tooltip in the meantime. normal-case/tracking-normal/ font-normal on the tooltip's own text counteracts the uppercase/ tracking-widest styling every caller's