fix(charts): move styles for d3 to the demo

src/app/pages/charts/d3/d3.component.scss

@@ -10,5 +10,28 @@
     display: block;
     width: 100%;
     height: 100%;
+
+    /deep/ {
+      .pie-label {
+        fill: nb-theme(color-fg-heading);
+      }
+
+      .grid-line-path {
+        stroke: nb-theme(separator);
+      }
+
+      text {
+        fill: nb-theme(color-fg-heading);
+      }
+
+      .chart-legend {
+        .legend-labels {
+          background: nb-theme(color-bg);
+        }
+        .legend-label {
+          color: nb-theme(color-fg-heading);
+        }
+      }
+    }
   }
 }