:root{--background-color: #f4f7f9;--container-bg: #ffffff;--primary-color: #4a90e2;--primary-hover: #357abd;--text-color: #333;--border-color: #ddd;--completed-color: #999;--delete-color: #e24a4a;--delete-hover: #c0392b;--shadow: 0 4px 6px rgba(0, 0, 0, .1)}body{margin:0;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-color:var(--background-color);color:var(--text-color)}.app-container{max-width:600px;margin:40px auto;padding:20px;background:var(--container-bg);border-radius:8px;box-shadow:var(--shadow)}header{text-align:center;border-bottom:1px solid var(--border-color);padding-bottom:20px;margin-bottom:20px}header h1{margin:0;color:var(--primary-color)}header p{margin:5px 0 0;color:#777}.add-todo-form{display:flex;gap:10px;margin-bottom:20px}.todo-input{flex-grow:1;padding:10px 15px;border:1px solid var(--border-color);border-radius:4px;font-size:1rem}.todo-input:focus{outline:none;border-color:var(--primary-color);box-shadow:0 0 0 2px #4a90e233}.add-btn,.delete-btn{padding:10px 15px;border:none;border-radius:4px;cursor:pointer;transition:background-color .2s ease;font-size:1rem;font-weight:700}.add-btn{background-color:var(--primary-color);color:#fff}.add-btn:hover{background-color:var(--primary-hover)}.todo-list{list-style-type:none;padding:0;margin:0}.todo-item{display:flex;align-items:center;justify-content:space-between;padding:12px 5px;border-bottom:1px solid var(--border-color);transition:background-color .2s ease}.todo-item:last-child{border-bottom:none}.todo-item.completed .todo-text{text-decoration:line-through;color:var(--completed-color)}.todo-item-main{display:flex;align-items:center;gap:15px}.todo-checkbox{width:20px;height:20px;cursor:pointer}.delete-btn{background:none;border:none;color:#ccc;font-size:1.5rem;line-height:1;padding:5px 10px}.delete-btn:hover{color:var(--delete-color)}.empty-state{text-align:center;color:#777;padding:20px}