*{box-sizing:border-box}body{font-family:Open Sans,system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,sans-serif;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;background-color:#f8f9fa;color:#2c3e50;line-height:1.6}.App{min-height:100vh;display:flex;flex-direction:column}.main-container{width:100%;max-width:800px;margin:0 auto}.content{flex:1;padding:2rem;background:#fff;min-height:calc(100vh - 140px);box-shadow:0 0 20px rgba(0,0,0,.05)}@media(max-width:768px){.main-container{flex-direction:column}.content{padding:1rem;min-height:auto}}.container{max-width:1200px;margin:0 auto;padding:0 2rem}.btn{display:inline-block;padding:.75rem 1.5rem;background:#3498db;color:#fff;text-decoration:none;border-radius:8px;border:none;cursor:pointer;font-size:1rem;font-weight:500;transition:all .3s ease}.btn:hover{background:#2980b9;transform:translateY(-2px);box-shadow:0 4px 12px rgba(52,152,219,.3)}.btn-secondary{background:#95a5a6}.btn-secondary:hover{background:#7f8c8d}.card{background:#fff;border-radius:12px;padding:1.5rem;box-shadow:0 4px 6px rgba(0,0,0,.1);transition:all .3s ease}.card:hover{transform:translateY(-4px);box-shadow:0 8px 25px rgba(0,0,0,.15)}.search-input{width:100%;padding:.75rem 1rem;border:2px solid #e9ecef;border-radius:8px;font-size:1rem;transition:border-color .3s ease}.search-input:focus{outline:none;border-color:#3498db;box-shadow:0 0 0 3px rgba(52,152,219,.1)}.loading{display:flex;justify-content:center;align-items:center;height:200px;font-size:1.2rem;color:#6c757d}.error{background:#f8d7da;color:#721c24;padding:1rem;border-radius:8px;border:1px solid #f5c6cb;margin:1rem 0}.vocab-btn{display:flex;align-items:center;background:none;border:none;font-weight:500;color:#c6c6c6;cursor:pointer;transition:all .2s;outline:none;text-align:left;padding-left:1rem;line-height:1.8}.vocab-btn .vocab-korean{font-size:1em;margin-right:1.2rem;min-width:80px}.vocab-btn .vocab-romanized{font-size:1rem;color:#6c757d;font-style:italic;min-width:120px}.vocab-btn .vocab-english{font-size:1.1rem;color:#495057;flex:1;text-align:left}.vocab-btn:focus,.vocab-btn:hover{color:#020202}.vocab-btn.selected{color:#020202;font-size:1.2rem;font-weight:600}.challenge-flex{display:flex;gap:2rem;align-items:flex-start;margin-bottom:2rem}.challenge-flex .vocab-list{display:flex;flex-direction:column;margin-bottom:2rem;max-width:250px;flex:0 0 320px}.page-header .change-day-btn{margin-left:1rem;margin-bottom:.5rem;cursor:pointer}.modal-overlay{position:fixed;top:0;left:0;right:0;bottom:0;background:rgba(0,0,0,.5);display:flex;justify-content:center;align-items:center;z-index:1000}.modal-content{background:#fff;padding:2rem;border-radius:8px;text-align:center;max-width:400px}.modal-select{margin-left:.5rem;font-size:.9rem;padding:.2rem .5rem;border-radius:4px;border:1px solid #ccc}.modal-buttons{margin-top:1.5rem}.modal-btn{padding:.5rem 1rem;color:#fff;border:none;border-radius:4px;cursor:pointer;margin-right:1rem}.modal-btn.primary{background:#3498db}.modal-btn.secondary{background:#95a5a6}@media(max-width:900px){.challenge-flex{flex-direction:column;gap:1.5rem}.challenge-flex .vocab-list{max-width:100%;width:100%;min-width:0;max-height:200px}}