Remove dark theme exclusive inset shadow from FloatingArrow (#2257)

ts/components/FloatingArrow.svelte

@@ -2,11 +2,7 @@
 Copyright: Ankitects Pty Ltd and contributors
 License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 -->
-<script lang="ts">
-    import { pageTheme } from "../sveltelib/theme";
-</script>
-
-<div class="arrow" class:dark={$pageTheme.isDark} />
+<div class="arrow" />
 
 <style lang="scss">
     @use "sass/elevation" as elevation;
@@ -23,9 +19,5 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
         /* Rotate the box to indicate the different directions */
         border-right: none;
         border-bottom: none;
-
-        &.dark {
-            box-shadow: inset 1px 1px 0 0 #565656;
-        }
     }
 </style>