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

packages/frontend/src/pages/auth.vue

@@ -5,7 +5,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 
 <template>
 <PageWithHeader :actions="headerActions" :tabs="headerTabs">
-	<MkSpacer :contentMax="500">
+	<div class="_spacer" style="--MI_SPACER-w: 500px;">
 		<div v-if="state == 'fetch-session-error'">
 			<p>{{ i18n.ts.somethingHappened }}</p>
 		</div>
@@ -36,7 +36,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 			<p :class="$style.loginMessage">{{ i18n.ts._auth.pleaseLogin }}</p>
 			<MkSignin @login="onLogin"/>
 		</div>
-	</MkSpacer>
+	</div>
 </PageWithHeader>
 </template>