:root{font-family:system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Oxygen,Ubuntu,Cantarell,Open Sans,Helvetica Neue,sans-serif;line-height:1.5}body{margin:0;display:flex;justify-content:center;min-width:320px;min-height:100vh;background:#f5f5f5}.todo-app{padding:2rem;max-width:600px;width:100%}.todo-form{display:flex;gap:.5rem;margin-bottom:1rem}.todo-input{flex:1;padding:.5rem;font-size:1rem;border:1px solid #ddd;border-radius:4px}.todo-button{padding:.5rem 1rem;font-size:1rem;background:#0066ff;color:#fff;border:none;border-radius:4px;cursor:pointer}.todo-button:hover{background:#0052cc}.todo-list{list-style:none;padding:0}.todo-item{display:flex;align-items:center;gap:.5rem;padding:.5rem;background:white;border-radius:4px;margin-bottom:.5rem}.todo-item.completed{text-decoration:line-through;opacity:.7}.todo-checkbox{width:1.2rem;height:1.2rem}.todo-text{flex:1}.todo-delete{padding:.25rem .5rem;background:#ff4444;color:#fff;border:none;border-radius:4px;cursor:pointer}.todo-delete:hover{background:#cc0000}