body, h1, ul, li, button, input {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: Arial, sans-serif;
}

body {
  background-color: #f4f4f9;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

.container {
  background: #fff;
  padding: 20px;
  border-radius: 10px;
  box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
  width: 300px;
}

h1 {
  font-size: 24px;
  margin-bottom: 20px;
  text-align: center;
  color: #333;
}

.input-container {
  display: flex;
  justify-content: space-between;
  margin-bottom: 20px;
}

input[type="text"] {
  flex: 1;
  padding: 10px;
  font-size: 16px;
  border: 1px solid #ddd;
  border-radius: 5px;
  margin-right: 10px;
}

button {
  padding: 10px;
  font-size: 16px;
  border: none;
  border-radius: 5px;
  background-color: #007bff;
  color: #fff;
  cursor: pointer;
  transition: background-color 0.3s;
}

button:hover {
  background-color: #0056b3;
}

ul {
  list-style: none;
}

li {
  background: #f9f9f9;
  padding: 10px;
  border: 1px solid #ddd;
  border-radius: 5px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 10px;
}

li.completed {
  text-decoration: line-through;
  color: #999;
}

li button {
  margin-left: 10px;
}

li button:first-of-type {
  background-color: #28a745;
}

li button:first-of-type:hover {
  background-color: #218838;
}

li button:last-of-type {
  background-color: #dc3545;
}

li button:last-of-type:hover {
  background-color: #c82333;
}