:root{--glass-bg: rgba(255, 255, 255, .05);--glass-border: rgba(255, 255, 255, .1);--accent-color: #ffd700;--text-color: #ffffff;--bg-color: #0f172a}body{margin:0;padding:0;font-family:Inter,system-ui,-apple-system,sans-serif;background-color:var(--bg-color);color:var(--text-color);display:flex;justify-content:center;align-items:center;min-height:100vh}.app-container{width:100%;max-width:650px;padding:3rem 2rem;background:#1e293bb3;backdrop-filter:blur(20px);-webkit-backdrop-filter:blur(20px);border:1px solid var(--glass-border);border-radius:32px;box-shadow:0 25px 50px -12px #00000080;text-align:center;margin:1rem}h1{font-size:2.2rem;margin-bottom:.5rem;color:var(--accent-color);letter-spacing:-.02em}h2{font-size:1.1rem;font-weight:300;opacity:.7;margin-bottom:2.5rem}.difficulty-controls{margin-bottom:1.5rem;display:flex;gap:.75rem;justify-content:center;flex-wrap:wrap}.action-controls{margin-bottom:2.5rem;display:flex;gap:1rem;justify-content:center}button{padding:.75rem 1.5rem;border-radius:12px;border:1px solid var(--glass-border);background:#ffffff1a;color:#fff;cursor:pointer;transition:all .2s cubic-bezier(.4,0,.2,1);font-size:.95rem;font-weight:500}button:hover{background:#ffffff26;transform:translateY(-2px);border-color:#ffffff4d}button.active{background:var(--accent-color);color:#000;border-color:var(--accent-color);box-shadow:0 0 15px #ffd7004d}.puzzle-board{display:grid;gap:6px;margin:0 auto;border-radius:16px;overflow:hidden;background:#020617;border:3px solid rgba(255,255,255,.05);box-shadow:0 20px 25px -5px #0000004d}.puzzle-tile{cursor:pointer;transition:transform .1s ease,filter .2s ease}.puzzle-tile:hover:not(.empty){filter:brightness(1.15) contrast(1.05);z-index:10}.puzzle-tile.empty{background:#1e293b;cursor:default}.overlay{position:fixed;inset:0;background:#000000d9;-webkit-backdrop-filter:blur(8px);backdrop-filter:blur(8px);display:flex;flex-direction:column;justify-content:center;align-items:center;z-index:1000;animation:overlayAppear .4s ease-out}@keyframes overlayAppear{0%{opacity:0;-webkit-backdrop-filter:blur(0px);backdrop-filter:blur(0px)}to{opacity:1;-webkit-backdrop-filter:blur(8px);backdrop-filter:blur(8px)}}.overlay-image{max-width:85%;max-height:70vh;border-radius:20px;box-shadow:0 0 50px #ffd70033;border:2px solid rgba(255,255,255,.1);object-fit:contain}.overlay-title{margin-top:2rem;color:var(--accent-color);font-size:1.8rem;font-weight:700;text-shadow:0 2px 10px rgba(0,0,0,.5)}.overlay-close{margin-top:1.5rem;background:var(--accent-color);color:#000;font-weight:600}