chore: 换用更美观、现代的前端页面 (#348)

web/src/lib/hooks/is-mobile.svelte.ts

@@ -0,0 +1,9 @@
+import { MediaQuery } from 'svelte/reactivity';
+
+const MOBILE_BREAKPOINT = 768;
+
+export class IsMobile extends MediaQuery {
+	constructor() {
+		super(`max-width: ${MOBILE_BREAKPOINT - 1}px`);
+	}
+}