Added "Shadow" set (Red, Green, Blue, transparent BG) (anuraghazra#2529)

* Added "Shadow" set (Red, Green, Blue, transparent BG)

3 additional themes sticking primarily to flat colors, which the exception of icons and border being slightly darker. All 3 themes also have transparent backgrounds that will show differently per-user via GiHub's own light and dark themes. Transparency should also still provide easy readability for both.

* Test

Just want to see if we can make the themes have a transparent background.

* Shadows moved under Transparent

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Co-authored-by: Zohan Subhash <zohan.subhash@gmail.com>

themes/index.js

@@ -18,6 +18,27 @@ export const themes = {
     text_color: "417E87",
     bg_color: "ffffff00",
   },
+  shadow_red: {
+    title_color: "9A0000",
+    text_color: "444",
+    icon_color: "4F0000",
+    border_color: "4F0000",
+    bg_color: "ffffff00",
+  },
+  shadow_green: {
+    title_color: "007A00",
+    text_color: "444",
+    icon_color: "003D00",
+    border_color: "003D00",
+    bg_color: "ffffff00",
+  },
+  shadow_blue: {
+    title_color: "00779A",
+    text_color: "444",
+    icon_color: "004450",
+    border_color: "004490",
+    bg_color: "ffffff00",
+  },
   dark: {
     title_color: "fff",
     icon_color: "79ff97",