优化每日编码时间的tooltip的显示

lib/screens/wakatime_screen.dart

@@ -472,7 +472,21 @@ class _WakatimeScreenState extends State<WakatimeScreen>
           '每日编码时间',
           style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold),
         ),
-        const SizedBox(height: 16),
+        SizedBox(
+          height: 40,
+          child: Center(
+            child: _touchedDayIndex != null
+                ? Text(
+                    '${_formatDate(DateTime.parse(dailyData[_touchedDayIndex!].range.date))}: ${_formatDuration(dailyData[_touchedDayIndex!].grandTotal.totalSeconds.toInt())}',
+                    style: const TextStyle(
+                      fontSize: 16,
+                      fontWeight: FontWeight.bold,
+                    ),
+                  )
+                : null,
+          ),
+        ),
+        // const SizedBox(height: 16),
         SizedBox(
           height: 200,
           child: BarChart(
@@ -571,18 +585,6 @@ class _WakatimeScreenState extends State<WakatimeScreen>
             ),
           ),
         ),
-        if (_touchedDayIndex != null) ...[
-          const SizedBox(height: 16),
-          Center(
-            child: Text(
-              '${_formatDate(DateTime.parse(dailyData[_touchedDayIndex!].range.date))}: ${_formatDuration(dailyData[_touchedDayIndex!].grandTotal.totalSeconds.toInt())}',
-              style: const TextStyle(
-                fontSize: 16,
-                fontWeight: FontWeight.bold,
-              ),
-            ),
-          ),
-        ],
       ],
     );
   }