:root{font-family:Segoe UI,ui-sans-serif,system-ui,-apple-system,sans-serif;line-height:1.5}*{box-sizing:border-box;margin:0;padding:0}html,body,#root{min-height:100vh;background:linear-gradient(135deg,#667eea,#764ba2);color:#2d3436}.app{min-height:100vh;padding:2rem 1.5rem;max-width:640px;margin:0 auto;display:flex;flex-direction:column;align-items:center}.header{text-align:center;margin-bottom:2rem}.title{font-size:2.2rem;font-weight:800;color:#fff;text-shadow:2px 2px 4px rgba(0,0,0,.2);margin-bottom:.25rem}.subtitle{font-size:1.1rem;color:#ffffffd9}.toggle-bar{display:flex;gap:.5rem;margin-bottom:1.5rem;background:#ffffff26;padding:4px;border-radius:12px}.toggle-btn{padding:.5rem 1.5rem;border:none;border-radius:10px;font-size:1.1rem;font-weight:700;cursor:pointer;background:transparent;color:#ffffffb3;transition:all .2s}.toggle-btn.active{background:#fff;color:#764ba2;box-shadow:0 2px 8px #00000026}.grid{display:grid;grid-template-columns:repeat(4,1fr);gap:.75rem;width:100%}@media(min-width:480px){.grid{grid-template-columns:repeat(6,1fr)}}.letter-tile{display:flex;flex-direction:column;align-items:center;justify-content:center;gap:.25rem;padding:.75rem .5rem;border:2px solid;border-radius:14px;cursor:pointer;transition:transform .15s,box-shadow .15s;font-family:inherit}.letter-tile:hover{transform:scale(1.08);box-shadow:0 4px 16px #0003}.letter-tile:active{transform:scale(.96)}.tile-letter{font-size:1.8rem;font-weight:800;color:#fff;line-height:1}.tile-emoji{font-size:1.2rem;line-height:1}.detail-card{background:#fff;border-radius:24px;border:4px solid;padding:2rem;width:100%;max-width:380px;text-align:center;box-shadow:0 8px 32px #0003;animation:popIn .3s ease}@keyframes popIn{0%{transform:scale(.8);opacity:0}to{transform:scale(1);opacity:1}}.back-btn{background:none;border:none;font-size:1rem;font-weight:600;color:#764ba2;cursor:pointer;padding:.25rem 0;margin-bottom:.5rem}.back-btn:hover{text-decoration:underline}.letter-display{font-size:6rem;font-weight:900;line-height:1;margin:.5rem 0}.letter-pair{font-size:1.4rem;font-weight:700;color:#555;margin-bottom:1rem}.upper{color:#764ba2}.divider{margin:0 .5rem;color:#ccc}.lower{color:#667eea}.word-section{display:flex;align-items:center;justify-content:center;gap:.75rem;background:#f8f9fa;border-radius:14px;padding:1rem;margin-bottom:1rem}.word-emoji{font-size:2.5rem}.word-text{font-size:1.6rem;color:#2d3436}.speak-btn{background:linear-gradient(135deg,#667eea,#764ba2);color:#fff;border:none;border-radius:12px;padding:.75rem 1.5rem;font-size:1.1rem;font-weight:700;cursor:pointer;transition:transform .15s,box-shadow .15s}.speak-btn:hover{transform:scale(1.05);box-shadow:0 4px 12px #667eea66}