Add Apple-inspired Flat Design style

styles.py

@@ -109,6 +109,28 @@ THEME_CONFIGS = {
         "tooltipBorderWidth": 0,
         "tooltipCornerRadius": 4,
         "uppercaseTooltip": False
+    },
+    "flat": {
+        "colors": [
+            "#ffadad", "#ffd6a5", "#fdffb6", "#caffbf", "#9bf6ff",
+            "#a0c4ff", "#bdb2ff", "#ffc6ff", "#ff9aa2", "#e2f0cb",
+            "#b5ead7"
+        ],
+        "fontFamily": "-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif",
+        "fontWeight": "500",
+        "pointStyle": "circle",
+        "textColorLight": "#1d1d1f",
+        "textColorDark": "#f5f5f7",
+        "borderColorLight": "#ffffff",
+        "borderColorDark": "#1c1c1e",
+        "borderWidth": 2,
+        "tooltipBg": "rgba(0, 0, 0, 0.8)",
+        "tooltipTitleColor": "#ffffff",
+        "tooltipBodyColor": "#ffffff",
+        "tooltipBorderColor": "transparent",
+        "tooltipBorderWidth": 0,
+        "tooltipCornerRadius": 12,
+        "uppercaseTooltip": False
     }
 }