Make icons white in dark mode

layouts/partials/docs/footer.html

@@ -8,7 +8,7 @@
   <div>
     {{ $date := .AuthorDate.Local.Format (default "January 2, 2006" $.Site.Params.BookDateFormat) }}
     <a class="flex align-center" href="{{ $.Site.Params.BookRepo }}/commit/{{ .Hash }}" title='{{ i18n "Last modified by" }} {{ .AuthorName }} | {{ $date }}' target="_blank">
-      <img src="{{ "svg/calendar.svg" | relURL }}" alt="Calendar" />
+      <img src="{{ "svg/calendar.svg" | relURL }}" class="book-icon" alt="Calendar" />
       <span>{{ $date }}</span>
     </a>
   </div>
@@ -18,7 +18,7 @@
   {{ if and .File .Site.Params.BookRepo .Site.Params.BookEditPath }}
   <div>
     <a class="flex align-center" href="{{ .Site.Params.BookRepo }}/{{ .Site.Params.BookEditPath }}/{{ .File.Path }}" target="_blank">
-      <img src="{{ "svg/edit.svg" | relURL }}" alt="Edit" />
+      <img src="{{ "svg/edit.svg" | relURL }}" class="book-icon" alt="Edit" />
       <span>{{ i18n "Edit this page" }}</span>
     </a>
   </div>

layouts/partials/docs/languages.html

@@ -11,7 +11,7 @@
 
   <ul>
     <li class="flex">
-      <img src="{{ "svg/translate.svg" | relURL }}" alt="Languages" />
+      <img src="{{ "svg/translate.svg" | relURL }}" class="book-icon" alt="Languages" />
       {{ $.Site.Language.LanguageName }}
     </li> 
   </ul>
@@ -20,7 +20,7 @@
     {{ range sort $langs }}
     <li class="{{ if (eq $.Site.Language .Language ) }}active{{ end }}">
       <a href="{{ .Permalink }}" class="flex">
-        <img src="{{ "svg/translate.svg" | relURL }}" alt="Languages" />
+        <img src="{{ "svg/translate.svg" | relURL }}" class="book-icon" alt="Languages" />
         {{ .Language.LanguageName }}
       </a>
     </li>

layouts/partials/docs/mobile-header.html

@@ -1,6 +1,6 @@
 <header class="flex align-center justify-between book-header">
   <label for="menu-control">
-    <img src="{{ "svg/menu.svg" | relURL }}" alt="Menu" />
+    <img src="{{ "svg/menu.svg" | relURL }}" class="book-icon" alt="Menu" />
   </label>
   <strong>{{ partial "docs/title" . }}</strong>
 </header>