Make icons white in dark mode

assets/_defaults.scss

@@ -41,9 +41,11 @@ $toc-width: 16rem !default;
 $md-breakpoint: $menu-width + $body-min-width * 1.25 + $toc-width !default;
 $sm-breakpoint: $menu-width + $body-min-width !default;
 
-// Panel colors
+// Hint colors
 $hint-colors: (
   info: #6bf,
   warning: #fd6,
   danger: #f66
 ) !default;
+
+$icon-filter: none !default;

assets/_main.scss

@@ -94,6 +94,10 @@ ul.pagination {
   margin: 0 auto;
 }
 
+.book-icon {
+  filter: $icon-filter;
+}
+
 .book-brand {
   margin-top: 0;
 
@@ -275,17 +279,6 @@ ul.pagination {
   }
 }
 
-.book-posts {
-  min-width: $body-min-width;
-  max-width: $body-min-width * 2;
-  flex-grow: 1;
-  padding: $padding-16;
-
-  article {
-    padding-bottom: $padding-16;
-  }
-}
-
 .book-home {
   padding: $padding-16;
 }

assets/plugins/_dark.scss

@@ -6,3 +6,5 @@ $body-font-color: #e9ecef;
 
 $color-link: #84b2ff;
 $color-visited-link: #b88dff;
+
+$icon-filter: brightness(0) invert(1);