Add custom theming for dark mode

Author: Mega-JC

docs/reST/themes/classic/static/pygame.css_t

@@ -709,13 +709,18 @@ dl.definition .admonition-title {
 
 div.note {
     background-color: {{ theme_notebgcolor }};
-    border: 1px solid #ccc;
+    border: 1px solid {{ theme_notebordercolor }};
 }
 
 .note tt {
     background: #d6d6d6;
 }
 
+.dark-theme div.note {
+    background-color: {{ theme_dark_notebgcolor }};
+    border: 1px solid {{ theme_dark_notebordercolor }};
+}
+
 div.seealso {
     background-color: #ffc;
     border: 1px solid #ff6;

docs/reST/themes/classic/theme.conf

@@ -51,6 +51,8 @@ dark_headertitlecolor       = #00ba10
 dark_headerlogoborder       = #00ba10
 dark_h1color                = #e1cd62
 dark_h2color                = #00b800
+dark_notebgcolor            = #45402f
+dark_notebordercolor        = #5e5740
 
 relbarbgcolor               = #6aee28
 relbartextcolor             = #000000
@@ -75,6 +77,7 @@ codekeyword                 = #DE6C90
 
 cautionbgcolor              = #eeffcc
 notebgcolor                 = #eeeeee
+notebordercolor             = #eeeeee
 
 highlightbgcolor            = #c7c695
 logobgcolor                 = #c2fc20