perf(frontend): use css-native implementation for spacer rather than vue component

packages/frontend/src/pages/gallery/post.vue

@@ -5,7 +5,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 
 <template>
 <PageWithHeader :actions="headerActions" :tabs="headerTabs">
-	<MkSpacer :contentMax="1000" :marginMin="16" :marginMax="32">
+	<div class="_spacer" style="--MI_SPACER-w: 1000px; --MI_SPACER-min: 16px; --MI_SPACER-max: 32px;">
 		<div class="_root">
 			<Transition :name="prefer.s.animation ? 'fade' : ''" mode="out-in">
 				<div v-if="post" class="rkxwuolj">
@@ -57,7 +57,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 				<MkLoading v-else/>
 			</Transition>
 		</div>
-	</MkSpacer>
+	</div>
 </PageWithHeader>
 </template>