*{margin:0;padding:0;box-sizing:border-box}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Oxygen,Ubuntu,Cantarell,Fira Sans,Droid Sans,Helvetica Neue,sans-serif;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;background:linear-gradient(135deg,#667eea,#764ba2);padding:20px}.app,body{min-height:100vh}.app{display:flex;justify-content:center;align-items:flex-start;padding:40px 20px}.container{background:white;border-radius:16px;box-shadow:0 20px 60px rgba(0,0,0,.3);width:100%;max-width:600px;padding:40px}header{margin-bottom:30px}.header-content{display:flex;justify-content:space-between;align-items:center}h1{font-size:2.5rem;color:#667eea;margin-bottom:8px;font-weight:700}.subtitle{color:#718096;font-size:1rem}.loading{text-align:center;padding:40px;color:#718096;font-size:1.1rem}.add-todo-form{display:flex;gap:10px;margin-bottom:24px}.todo-input{flex:1 1;padding:14px 18px;border:2px solid #e2e8f0;border-radius:8px;font-size:1rem;transition:all 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