New: Darkmode

* New: Native Theme Engine

Co-Authored-By: Zak Saunders <thezak48@users.noreply.github.com>
(cherry picked from commit 2291f3e00eb2ff9268a0b2f49da8dde82ee13c04)

* Update CSS for themes

* Fixup CSS values

* Fixup remove duped Color-Impaired setting

* Fixup Link Colors

Co-Authored-By: Qstick <qstick@gmail.com>

frontend/src/Author/Details/AuthorDetailsHeader.css

@@ -16,7 +16,7 @@
   position: absolute;
   width: 100%;
   height: 100%;
-  background: $black;
+  background: var(--black);
   opacity: 0.7;
 }
 
@@ -25,7 +25,7 @@
   padding: 30px;
   width: 100%;
   height: 100%;
-  color: $white;
+  color: var(--white);
 }
 
 .poster {
@@ -69,7 +69,7 @@
   width: 40px;
 
   &:hover {
-    color: $iconButtonHoverLightColor;
+    color: var(--iconButtonHoverLightColor);
   }
 }
 
@@ -97,7 +97,7 @@
   white-space: nowrap;
 
   &:hover {
-    color: $iconButtonHoverLightColor;
+    color: var(--iconButtonHoverLightColor);
   }
 }