feat(ui): warm library palette (zinc+emerald -> stone+amber) with hover/focus feedback; text reader gains paper/sepia/night themes + persisted font-size (lib/readerPrefs.ts), serif justified measure; PDF drops emoji icons for 首页/末页, CBZ pill page counter, EPUB centered spread, blur reader header with format badge, aria labels on login/search/chapter select

frontend/src/readers/EpubReader.tsx

@@ -91,11 +91,11 @@ export default function EpubReader({ book, initialLocator }: ReaderProps) {
 
   return (
     <div className="grid h-full grid-rows-[1fr_auto]">
-      <div className="relative min-h-0 bg-white">
+      <div className="relative mx-auto min-h-0 w-full max-w-4xl bg-white shadow-2xl ring-1 ring-stone-800">
         <div ref={hostRef} className="absolute inset-0" />
-        {!ready && !err && <div className="grid h-full place-items-center bg-zinc-950 text-zinc-500">EPUB 加载中…</div>}
+        {!ready && !err && <div className="grid h-full place-items-center bg-stone-950 text-stone-500">EPUB 加载中…</div>}
       </div>
-      <div className="flex items-center justify-center gap-3 border-t border-zinc-800 px-4 py-2 text-sm">
+      <div className="flex items-center justify-center gap-3 border-t border-stone-800 px-4 py-2 text-sm">
         <button className={btn} onClick={() => rendRef.current?.prev()}>
           上一页
         </button>