Fix chart height - override flex with explicit 380px

- Add .exportable-chart.chart-container rule with flex:none and height:380px
- This overrides the flex:1 that was preventing height from being applied
- Also fixed .chart-section .chart-container to 380px

src/App.css

@@ -1089,7 +1089,7 @@ table tbody tr:hover {
 }
 
 .chart-section .chart-container {
-  height: 300px;
+  height: 380px;
 }
 
 /* Desktop/Mobile visibility */
@@ -1908,6 +1908,12 @@ html[dir="rtl"] .chart-header-with-export {
   min-height: 0;
 }
 
+/* Explicit height when chart-container class is applied */
+.exportable-chart.chart-container {
+  flex: none;
+  height: 380px;
+}
+
 /* Download button - always top corner, outside normal flow */
 .chart-export-btn,
 .chart-export-btn.visible {