/* LineChart — line / area trend scaffold. Covers a single-series area
   (flat ~10% wash, metric selector, day/week/month toggle, hover crosshair)
   and a dual-series line (legend series toggle, goal-event dropdown, hover
   read-out). Chart-norm rebuild (owner decision 2026-07-07): 2px lines in
   --chart-1/--chart-2, solid hairline gridlines (never dashed), a flat area
   wash only on the single series, ≥8px markers with a 2px surface ring, the
   endpoint direct-labeled, and tooltips where the value leads and the series
   is keyed by a short line stroke.
   Data-rigor rules (2026-07-08): lines are for CONTINUOUS measures sampled
   over time — discrete per-bucket counts belong to columns. Lines draw
   STRAIGHT segments between samples (owner call 2026-07-08, superseding the
   smooth-curve round): the points are bucketed aggregates, so a spline
   invents visible between-point wiggles at readable spacing. Cosmetic
   smoothing is allowed only on dense series (≳30 points, point gap too
   small to show a curve feature) and only with monotone interpolation that
   cannot overshoot a sample; read-outs always return the sampled value,
   never an interpolated one. Bars must be zero-based, but a
   line may window its y-range — the area wash must then fade to transparent
   (never a solid fill on a truncated axis). A granularity toggle (D/W/M)
   re-picks the mark for the new density: <8 points → columns/dots, 8–31 →
   line with hover markers, >31 → thin line with endpoint label only — and
   keeps ~5–8 labeled ticks at every density. Two series of different units
   draw on independent scales ONLY when declared (sub + aria), or share an
   indexed base. Visual source: tokens.css. */

.line-chart {
  box-sizing: border-box;
  display: flex;
  flex-direction: column;
  gap: 16px;
  width: 100%;
  max-width: 1126px;
  padding: 21px;
  background: var(--canvas);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  box-shadow: var(--shadow-1);
  font-family: var(--font-sans);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
}

.line-chart__head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
}
.line-chart__title-wrap {
  display: flex;
  align-items: center;
  gap: 12px;
}
.line-chart__title {
  margin: 0;
  font-size: var(--fs-6);
  font-weight: var(--fw-heavy);
  letter-spacing: -0.01em;
}
.line-chart__sub {
  margin: 2px 0 0;
  font-size: var(--fs-2);
  color: var(--text-4);
}
.line-chart__controls {
  display: flex;
  align-items: center;
  gap: 10px;
}

/* Day / Week / Month segmented toggle. */
.line-chart__seg {
  display: inline-flex;
  padding: 2px;
  border-radius: var(--r-full);
  background: var(--surface-2);
}
.line-chart__seg-btn {
  height: 26px;
  min-width: 28px;
  padding: 0 10px;
  border: 0;
  border-radius: var(--r-full);
  background: transparent;
  font: inherit;
  font-size: var(--fs-2);
  font-weight: var(--fw-semibold);
  color: var(--text-4);
  cursor: pointer;
  transition:
    background var(--dur-2) var(--ease-out),
    color var(--dur-2) var(--ease-out);
}
.line-chart__seg-btn:hover:not([aria-pressed='true']) {
  color: var(--text-2);
}
.line-chart__seg-btn[aria-pressed='true'] {
  background: var(--canvas);
  color: var(--text);
  box-shadow: var(--shadow-1);
}
.line-chart__seg-btn:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
}

/* Bordered metric selector (single-series variant). */
.line-chart__select {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  height: 30px;
  padding: 0 12px;
  border: 1px solid var(--border);
  border-radius: var(--r-full);
  background: var(--surface);
  font: inherit;
  font-size: var(--fs-2);
  font-weight: var(--fw-semibold);
  color: var(--text);
  cursor: pointer;
  transition: background var(--dur-2) var(--ease-out);
}
.line-chart__select:hover {
  background: var(--surface-2);
}
.line-chart__select svg {
  color: var(--text-4);
}
.line-chart__select:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
}

/* Legend (dual-series variant). */
.line-chart__legend {
  display: flex;
  align-items: center;
  gap: 16px;
}
.line-chart__legend-item {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  border: 0;
  background: transparent;
  font: inherit;
  font-size: var(--fs-2);
  color: var(--text-4);
  cursor: pointer;
  transition:
    opacity var(--dur-2) var(--ease-out),
    color var(--dur-2) var(--ease-out);
}
.line-chart__legend-item:hover {
  color: var(--text-2);
}
.line-chart__legend-item[aria-pressed='false'] {
  opacity: 0.4;
}
.line-chart__legend-item:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
  border-radius: var(--r-sm);
}
.line-chart__swatch {
  width: 20px;
  height: 2px;
  border-radius: 1px;
  flex: none;
}
.line-chart__swatch--sessions {
  background: var(--chart-1-line);
}
.line-chart__swatch--goal {
  background: var(--chart-2);
}

/* Inline dropdown (goal event). */
.line-chart__dropdown {
  position: relative;
  display: inline-flex;
  align-items: center;
}
.line-chart__dropdown-toggle {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  border: 0;
  background: transparent;
  font: inherit;
  font-size: var(--fs-2);
  font-weight: var(--fw-semibold);
  color: var(--text);
  cursor: pointer;
  transition: color var(--dur-2) var(--ease-out);
}
.line-chart__dropdown-toggle:hover {
  color: var(--ink-900);
}
.line-chart__dropdown-toggle svg {
  color: var(--text-4);
  transition: transform var(--dur-2) var(--ease-out);
}
.line-chart__dropdown.is-open .line-chart__dropdown-toggle svg {
  transform: rotate(180deg);
}
.line-chart__menu {
  position: absolute;
  top: calc(100% + 6px);
  right: 0;
  z-index: 5;
  display: none;
  flex-direction: column;
  min-width: 160px;
  padding: 5px;
  border: 1px solid var(--border);
  border-radius: var(--r-md);
  background: var(--surface-glass-strong);
  box-shadow: var(--shadow-2);
  backdrop-filter: blur(16px) saturate(1.1);
  -webkit-backdrop-filter: blur(16px) saturate(1.1);
}
.line-chart__dropdown.is-open .line-chart__menu {
  display: flex;
}
.line-chart__menu-item {
  display: flex;
  align-items: center;
  height: 32px;
  padding: 0 10px;
  border: 0;
  border-radius: var(--r-sm);
  background: transparent;
  font: inherit;
  font-size: var(--fs-2);
  font-weight: var(--fw-medium);
  color: var(--text-2);
  text-align: left;
  cursor: pointer;
  transition:
    background var(--dur-2) var(--ease-out),
    color var(--dur-2) var(--ease-out);
}
.line-chart__menu-item:hover {
  background: var(--ink-soft);
  color: var(--text);
}
.line-chart__menu-item[aria-selected='true'] {
  color: var(--text);
  font-weight: var(--fw-semibold);
}

/* Plot. */
/* Body: labeled y-axis gutter(s) + stretch plot. Dual-axis charts label each
   side in its series' color — the scale must be readable without hover. */
.line-chart__body {
  display: flex;
  gap: 10px;
}
.line-chart__yaxis {
  position: relative;
  flex: none;
  width: 34px;
}
.line-chart__yaxis--right {
  width: 30px;
}
.line-chart__ytick {
  position: absolute;
  right: 0;
  transform: translateY(-50%);
  font-size: var(--fs-2);
  color: var(--text-4);
  font-variant-numeric: tabular-nums;
}
.line-chart__yaxis--right .line-chart__ytick {
  right: auto;
  left: 0;
}
.line-chart__ytick--sessions {
  color: var(--chart-1-strong);
  font-weight: var(--fw-semibold);
}
.line-chart__ytick--goal {
  color: var(--text-2);
  font-weight: var(--fw-semibold);
}

/* Reference marks (average / target / benchmark): the only DASHED line in a
   chart — gridlines stay solid so references stand apart. Always labeled. */
.line-chart__ref {
  stroke: var(--text-4);
  stroke-width: 1;
  stroke-dasharray: 4 4;
}
.line-chart__ref-label {
  position: absolute;
  transform: translateY(-50%);
  padding: 1px 7px;
  border-radius: var(--r-full);
  background: var(--canvas);
  border: 1px dashed var(--border-strong);
  color: var(--text-3);
  font-size: var(--fs-1);
  font-weight: var(--fw-semibold);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

.line-chart__plot {
  position: relative;
  width: 100%;
  min-width: 0;
  flex: 1;
}
.line-chart__plot svg {
  display: block;
  width: 100%;
  height: auto;
}
.line-chart__grid {
  stroke: var(--border);
  stroke-width: 1;
}
.line-chart__baseline {
  stroke: var(--border-strong);
  stroke-width: 1;
}
.line-chart__series {
  transition: opacity var(--dur-2) var(--ease-out);
}
.line-chart__series.is-series-hidden {
  opacity: 0;
  pointer-events: none;
}

.line-chart__point {
  opacity: 0;
  transition: opacity var(--dur-1) var(--ease-out);
}
.line-chart__plot.is-hovering .line-chart__point {
  opacity: 1;
}
/* Endpoint marker — ink point on the bright line, 2px surface ring. */
.line-chart__static-point {
  fill: var(--chart-emphasis);
  stroke: var(--canvas);
  stroke-width: 2;
}
.line-chart__static-point--goal {
  fill: var(--chart-2);
}
/* Crosshair — a solid hairline that snaps to the nearest X. */
.line-chart__guide {
  opacity: 0;
  stroke: var(--border-strong);
  stroke-width: 1;
}
.line-chart__plot.is-hovering .line-chart__guide {
  opacity: 1;
}

/* Endpoint direct label (HTML overlay — ink, never the series color). */
.line-chart__end-label {
  position: absolute;
  transform: translateY(-50%);
  padding: 2px 7px;
  border-radius: var(--r-full);
  background: var(--canvas);
  border: 1px solid var(--border);
  color: var(--text-2);
  font-size: var(--fs-1);
  font-weight: var(--fw-bold);
  font-variant-numeric: tabular-nums;
  pointer-events: none;
}

/* Tooltip — compact dual-series read-out. */
.line-chart__tooltip {
  position: absolute;
  top: 0;
  left: 0;
  z-index: 6;
  display: none;
  flex-direction: column;
  gap: 3px;
  padding: 8px 10px;
  border: 1px solid var(--border);
  border-radius: var(--r-md);
  background: var(--surface-glass-strong);
  box-shadow: var(--shadow-2);
  font-size: var(--fs-1);
  white-space: nowrap;
  pointer-events: none;
  transform: translate(-50%, calc(-100% - 12px));
  backdrop-filter: blur(16px) saturate(1.1);
  -webkit-backdrop-filter: blur(16px) saturate(1.1);
}
.line-chart__plot.is-hovering .line-chart__tooltip {
  display: flex;
}
.line-chart__tooltip-date {
  color: var(--text-4);
  font-weight: var(--fw-semibold);
}
/* Value leads, series label follows; the series is keyed by a short line
   stroke (never a filled box) — the legend's hierarchy inverted. */
.line-chart__tooltip-row {
  display: flex;
  align-items: center;
  gap: 6px;
  color: var(--text-3);
}
.line-chart__tooltip-row b {
  color: var(--text);
  font-weight: var(--fw-heavy);
  font-size: var(--fs-2);
  font-variant-numeric: tabular-nums;
}
.line-chart__tooltip-key {
  width: 10px;
  height: 2px;
  border-radius: 1px;
  flex: none;
}

/* Tooltip — dark value badge (single-series variant). */
.line-chart__badge {
  position: absolute;
  top: 0;
  left: 0;
  z-index: 6;
  display: none;
  padding: 4px 9px;
  border-radius: var(--r-md);
  background: var(--ink-900);
  color: #fff;
  font-size: var(--fs-1);
  font-weight: var(--fw-heavy);
  white-space: nowrap;
  pointer-events: none;
  transform: translate(-50%, calc(-100% - 12px));
}
.line-chart__plot.is-hovering .line-chart__badge {
  display: block;
}

.line-chart__axis {
  display: flex;
  justify-content: space-between;
  margin-top: 6px;
  padding: 0 4px;
}
/* Offset past the y-axis gutter(s) so x labels align with the plot. */
.line-chart__axis--gutter-l {
  padding-left: 48px;
}
.line-chart__axis--gutter-lr {
  padding-left: 48px;
  padding-right: 44px;
}
.line-chart__axis span {
  font-size: var(--fs-2);
  color: var(--text-4);
}

/* Trend caption pill (single-series). */
.line-chart__caption {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  align-self: flex-start;
  padding: 4px 10px;
  border-radius: var(--r-full);
  background: var(--pulse-cyan-soft);
  color: var(--pulse-cyan-dark);
  font-size: var(--fs-2);
  font-weight: var(--fw-semibold);
}

/* Stat-first hero — the widget leads with its number; the chart is evidence
   (owner-approved reference anatomy: kicker → hero value → chart). */
.line-chart__hero {
  display: flex;
  align-items: baseline;
  gap: 10px;
  margin-top: -6px;
}
.line-chart__hero-value {
  font-size: var(--fs-9);
  font-weight: var(--fw-heavy);
  line-height: 1;
  letter-spacing: -0.02em;
}
.line-chart__hero-delta {
  font-size: var(--fs-2);
  font-weight: var(--fw-semibold);
  color: var(--success-600);
}