:root{font-family:Segoe UI,system-ui,-apple-system,sans-serif;line-height:1.5}*{box-sizing:border-box;margin:0;padding:0}html,body,#root{min-height:100vh;overflow-x:hidden}body{background:linear-gradient(135deg,#667eea,#764ba2)}#root{display:flex;flex-direction:column;align-items:center;padding:1rem}.app-header{text-align:center;margin-bottom:1.5rem}.app-header h1{font-size:2.2rem;color:#fff;text-shadow:2px 2px 4px rgba(0,0,0,.2);font-weight:800}.app-header .subtitle{color:#ffffffd9;font-size:1rem;margin-top:.25rem}.mode-toggle{display:flex;gap:.5rem;margin-bottom:1.5rem}.mode-btn{padding:.6rem 1.4rem;border:3px solid rgba(255,255,255,.4);border-radius:2rem;background:#ffffff26;color:#fff;font-size:1rem;font-weight:700;cursor:pointer;transition:all .2s;-webkit-backdrop-filter:blur(4px);backdrop-filter:blur(4px)}.mode-btn:hover{background:#ffffff4d;transform:translateY(-1px)}.mode-btn.active{background:#fff;color:#764ba2;border-color:#fff;box-shadow:0 4px 15px #0003}.letter-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(70px,1fr));gap:.6rem;max-width:700px;width:100%;margin-bottom:2rem}.letter-tile{aspect-ratio:1;display:flex;align-items:center;justify-content:center;font-size:2rem;font-weight:800;border-radius:1rem;cursor:pointer;border:3px solid transparent;transition:all .2s;color:#fff;text-shadow:1px 1px 2px rgba(0,0,0,.2);position:relative}.letter-tile:hover{transform:scale(1.1);box-shadow:0 6px 20px #0000004d;z-index:1}.letter-tile:active{transform:scale(.95)}.letter-tile.learned{border-color:#4ade80}.letter-tile.learned:after{content:"✓";position:absolute;top:2px;right:6px;font-size:.7rem;color:#4ade80}.detail-overlay{position:fixed;top:0;right:0;bottom:0;left:0;background:#00000080;display:flex;align-items:center;justify-content:center;z-index:100;padding:1rem;animation:fadeIn .2s ease}@keyframes fadeIn{0%{opacity:0}to{opacity:1}}@keyframes popIn{0%{transform:scale(.8);opacity:0}to{transform:scale(1);opacity:1}}.detail-card{background:#fff;border-radius:2rem;padding:2rem;max-width:420px;width:100%;text-align:center;position:relative;animation:popIn .3s ease;box-shadow:0 20px 60px #0000004d}.detail-close{position:absolute;top:1rem;right:1.2rem;background:none;border:none;font-size:1.8rem;cursor:pointer;color:#999;line-height:1}.detail-close:hover{color:#333}.detail-letter{font-size:7rem;font-weight:900;line-height:1;margin:.5rem 0;cursor:pointer;transition:transform .15s;display:inline-block}.detail-letter:hover{transform:scale(1.05)}.detail-letter:active{transform:scale(.95)}.detail-both{font-size:1.4rem;color:#666;font-weight:600;margin-bottom:.5rem}.detail-phonics{font-size:1.1rem;color:#8b5cf6;font-weight:600;margin-bottom:1rem}.detail-word{font-size:2.5rem;font-weight:800;color:#1a1a2e;margin-bottom:.5rem}.detail-emoji{font-size:5rem;margin-bottom:1rem}.detail-sentence{font-size:1.05rem;color:#555;margin-bottom:1.5rem;font-style:italic}.detail-speak-btn{background:linear-gradient(135deg,#667eea,#764ba2);color:#fff;border:none;padding:.8rem 2rem;border-radius:2rem;font-size:1.1rem;font-weight:700;cursor:pointer;transition:transform .15s,box-shadow .15s;box-shadow:0 4px 15px #667eea66}.detail-speak-btn:hover{transform:translateY(-2px);box-shadow:0 6px 20px #667eea80}.detail-speak-btn:active{transform:translateY(0)}.detail-nav{display:flex;justify-content:space-between;margin-top:1.5rem}.detail-nav button{background:#f0f0f0;border:none;padding:.5rem 1.2rem;border-radius:1rem;font-size:1rem;cursor:pointer;font-weight:600;color:#555;transition:background .15s}.detail-nav button:hover{background:#e0e0e0}.detail-nav button:disabled{opacity:.3;cursor:default}.quiz-container{background:#fff;border-radius:2rem;padding:2.5rem 2rem;max-width:450px;width:100%;text-align:center;box-shadow:0 20px 60px #0003}.quiz-progress{display:flex;gap:4px;margin-bottom:1.5rem;justify-content:center}.quiz-dot{width:12px;height:12px;border-radius:50%;background:#e0e0e0;transition:background .3s}.quiz-dot.correct{background:#4ade80}.quiz-dot.wrong{background:#f87171}.quiz-dot.current{background:#8b5cf6;animation:pulse 1s infinite}@keyframes pulse{0%,to{transform:scale(1)}50%{transform:scale(1.3)}}.quiz-prompt{font-size:1.2rem;color:#555;margin-bottom:.5rem;font-weight:600}.quiz-letter{font-size:8rem;font-weight:900;color:#1a1a2e;line-height:1.1;margin-bottom:1.5rem;cursor:pointer;transition:transform .15s}.quiz-letter:hover{transform:scale(1.05)}.quiz-letter:active{transform:scale(.95)}.quiz-options{display:grid;grid-template-columns:1fr 1fr;gap:.8rem;margin-bottom:1rem}.quiz-option{padding:1rem;border:3px solid #e0e0e0;border-radius:1rem;background:#fff;font-size:1.8rem;font-weight:700;cursor:pointer;transition:all .15s;color:#333}.quiz-option:hover{border-color:#8b5cf6;background:#f5f3ff}.quiz-option.selected-correct{border-color:#4ade80;background:#f0fdf4;color:#16a34a}.quiz-option.selected-wrong{border-color:#f87171;background:#fef2f2;color:#dc2626}.quiz-option.reveal-correct{border-color:#4ade80;background:#f0fdf4}.quiz-result{margin-top:1.5rem}.quiz-result h2{font-size:1.8rem;color:#1a1a2e;margin-bottom:.5rem}.quiz-result p{color:#666;font-size:1.1rem;margin-bottom:1.5rem}.quiz-result .score{font-size:4rem;font-weight:900;background:linear-gradient(135deg,#667eea,#764ba2);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}.quiz-restart{background:linear-gradient(135deg,#667eea,#764ba2);color:#fff;border:none;padding:.8rem 2.5rem;border-radius:2rem;font-size:1.1rem;font-weight:700;cursor:pointer;margin-top:1rem;transition:transform .15s}.quiz-restart:hover{transform:translateY(-2px)}@media(max-width:500px){.letter-grid{grid-template-columns:repeat(auto-fill,minmax(55px,1fr));gap:.4rem}.letter-tile{font-size:1.5rem;border-radius:.75rem}.detail-letter,.quiz-letter{font-size:5rem}.app-header h1{font-size:1.6rem}}