fix: improve chart tooltips

components/charts/chart-tooltip.tsx

@@ -0,0 +1,49 @@
+import type { ReactNode } from "react";
+
+interface ChartTooltipPayload {
+  color?: string;
+  dataKey?: string | number;
+  name?: ReactNode;
+  payload?: Record<string, unknown>;
+  value?: unknown;
+}
+
+interface ChartTooltipProps {
+  active?: boolean;
+  label?: ReactNode;
+  labelFormatter?: (label: ReactNode) => ReactNode;
+  payload?: ChartTooltipPayload[];
+  valueFormatter?: (entry: ChartTooltipPayload) => ReactNode;
+}
+
+export function ChartTooltip({ active, label, labelFormatter, payload, valueFormatter }: ChartTooltipProps) {
+  if (!active || !payload?.length) return null;
+
+  return (
+    <div className="min-w-36 rounded-card border border-border/80 bg-surface-raised/95 px-3.5 py-3 text-xs text-foreground shadow-card backdrop-blur-xl">
+      {label !== undefined && (
+        <p className="mb-2 text-[0.68rem] font-semibold uppercase tracking-[0.14em] text-muted">
+          {labelFormatter ? labelFormatter(label) : label}
+        </p>
+      )}
+      <div className="space-y-1.5">
+        {payload.map((entry, index) => (
+          <div
+            className="grid grid-cols-[minmax(0,1fr)_auto] items-center gap-4"
+            key={`${String(entry.dataKey ?? entry.name ?? "series")}-${index}`}
+          >
+            <span className="flex min-w-0 items-center gap-2 text-muted">
+              {entry.color && (
+                <span className="size-2 rounded-full" style={{ backgroundColor: entry.color }} aria-hidden="true" />
+              )}
+              <span className="truncate">{entry.name}</span>
+            </span>
+            <span className="font-semibold tabular-nums text-foreground">
+              {valueFormatter ? valueFormatter(entry) : String(entry.value ?? "—")}
+            </span>
+          </div>
+        ))}
+      </div>
+    </div>
+  );
+}

components/charts/day-forecast-charts.tsx

@@ -2,6 +2,7 @@
 
 import { Bar, CartesianGrid, ComposedChart, Legend, Line, ResponsiveContainer, Tooltip, XAxis, YAxis } from "recharts";
 import { Card } from "@/components/ui/card";
+import { ChartTooltip } from "@/components/charts/chart-tooltip";
 import { CHART_COLORS } from "@/lib/chart-theme";
 import { useI18n } from "@/lib/i18n";
 import { formatForecastRainfall, formatForecastTemperature } from "@/lib/forecast-utils";
@@ -56,17 +57,16 @@ export function DayForecastCharts({ hours }: { hours: HourlyForecast[] }) {
                 unit={temperatureUnitLabel}
               />
               <Tooltip
-                contentStyle={{
-                  borderRadius: 14,
-                  border: `1px solid ${CHART_COLORS.tooltipBorder}`,
-                  background: CHART_COLORS.tooltipBackground,
-                  color: CHART_COLORS.tooltipText,
-                }}
-                formatter={(value) => [
-                  typeof value === "number"
-                    ? formatTemperatureValue(value, language, temperatureUnit)
-                    : formatForecastTemperature(null, language, temperatureUnit),
-                ]}
+                cursor={{ stroke: CHART_COLORS.grid, strokeDasharray: "4 4" }}
+                content={
+                  <ChartTooltip
+                    valueFormatter={(entry) =>
+                      typeof entry.value === "number"
+                        ? formatTemperatureValue(entry.value, language, temperatureUnit)
+                        : formatForecastTemperature(null, language, temperatureUnit)
+                    }
+                  />
+                }
               />
               <Legend wrapperStyle={{ fontSize: "0.72rem" }} />
               <Line
@@ -130,18 +130,16 @@ export function DayForecastCharts({ hours }: { hours: HourlyForecast[] }) {
                 unit="%"
               />
               <Tooltip
-                contentStyle={{
-                  borderRadius: 14,
-                  border: `1px solid ${CHART_COLORS.tooltipBorder}`,
-                  background: CHART_COLORS.tooltipBackground,
-                  color: CHART_COLORS.tooltipText,
-                }}
-                formatter={(value, name) => [
-                  name === t("forecast.precipitation")
-                    ? formatForecastRainfall(typeof value === "number" ? value : null, language)
-                    : `${typeof value === "number" ? value : "—"}%`,
-                  name,
-                ]}
+                cursor={{ fill: "hsl(var(--border) / 0.18)" }}
+                content={
+                  <ChartTooltip
+                    valueFormatter={(entry) =>
+                      entry.dataKey === "precipitation"
+                        ? formatForecastRainfall(typeof entry.value === "number" ? entry.value : null, language)
+                        : `${typeof entry.value === "number" ? entry.value : "—"}%`
+                    }
+                  />
+                }
               />
               <Legend wrapperStyle={{ fontSize: "0.72rem" }} />
               <Bar

components/charts/snapshot-chart.tsx

@@ -2,6 +2,7 @@
 
 import { Bar, BarChart, Cell, ResponsiveContainer, Tooltip, XAxis, YAxis } from "recharts";
 import type { SynopStation } from "@/types/imgw";
+import { ChartTooltip } from "@/components/charts/chart-tooltip";
 import { Card } from "@/components/ui/card";
 import { useI18n } from "@/lib/i18n";
 import { useWeatherStore } from "@/lib/store";
@@ -56,7 +57,14 @@ export function SnapshotChart({ station }: { station: SynopStation }) {
             />
             <Tooltip
               cursor={{ fill: "hsl(var(--border) / 0.22)" }}
-              formatter={(_, __, item) => [`${item.payload.value} ${item.payload.unit}`, item.payload.name]}
+              content={
+                <ChartTooltip
+                  valueFormatter={(entry) => {
+                    const row = entry.payload;
+                    return `${row?.value ?? "—"} ${row?.unit ?? ""}`.trim();
+                  }}
+                />
+              }
             />
             <Bar dataKey="normalized" radius={[0, 8, 8, 0]} barSize={14}>
               {rows.map((row) => (