creation and implementation of selection variable

src/dark.scss

@@ -1,6 +1,8 @@
 $background: #202b38 !default;
 $background-alt: #161f27 !default;
 
+$selection: #161f27 !default;
+
 $text-main: #dbdbdb !default;
 $text-bright: #ffffff !default;
 

src/light.scss

@@ -1,6 +1,8 @@
 $background: #ffffff !default;
 $background-alt: #efefef !default;
 
+$selection: #9e9e9e !default;
+
 $text-main: #363636 !default;
 $text-bright: #000000 !default;
 

src/parts/_misc.scss

@@ -43,4 +43,8 @@ tbody tr:nth-child(even) {
 
 ::-webkit-scrollbar-thumb:hover {
   background: $scrollbar-thumb-hover;
+}
+
+::selection {
+  background-color: $selection;
 }