* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: Arial, sans-serif;
  background-color: #f4f4f9;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

.container {
  text-align: center;
  background-color: white;
  padding: 20px;
  border-radius: 8px;
  box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
  width: 300px;
}

input[type="text"] {
  width: 80%;
  padding: 10px;
  margin-bottom: 10px;
  border: 1px solid #ccc;
  border-radius: 4px;
}

button {
  padding: 10px;
  background-color: #4CAF50;
  color: white;
  border: none;
  border-radius: 4px;
  cursor: pointer;
}

button:hover {
  background-color: #45a049;
}

ul {
  list-style: none;
  padding: 0;
  margin-top: 20px;
}

li {
  background-color: #f2f2f2;
  padding: 10px;
  margin: 5px 0;
  border-radius: 4px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

li.completed {
  background-color: #d4edda;
  text-decoration: line-through;
  color: green;
}

button.complete {
  background-color: #28a745;
  cursor: pointer;
}

button.complete:hover {
  background-color: #218838;
}