fix(front): use theme-aware background color on root elements

front/src/App.vue

@@ -141,6 +141,10 @@ store.dispatch('auth/fetchUser')
 }
 </style>
 <style>
+html, body {
+    background-color: var(--background-color);
+}
+
 /* Make inert pages (behind modals) unscrollable */
 body:has(#app[inert="true"]) {
   overflow: hidden;

front/src/style/colors.scss

@@ -85,6 +85,10 @@
 
 // Light theme
 
+:root:has(body.theme-light) {
+    --background-color: var(--fw-beige-100);
+}
+
 :is(body.theme-light, html:not(.dark) > body:not(.theme-dark)),
 .force-light-theme.force-light-theme.force-light-theme {
   --focus-ring-color: var(--fw-primary);
@@ -328,6 +332,10 @@
 
 // Dark theme
 
+:root:has(body.theme-dark) {
+    --background-color: var(--fw-gray-960);
+}
+
 :is(body.theme-dark, html.dark > body:not(.theme-light)),
 .force-dark-theme.force-dark-theme.force-dark-theme {
   --focus-ring-color: var(--fw-gray-600);