body {
  font-family: Arial, sans-serif;
  background: #f5f5f5;
  padding: 30px;
}

.container {
  max-width: 500px;
  margin: auto;
  background: white;
  padding: 20px;
  border-radius: 10px;
}

input, button {
  padding: 10px;
  margin-right: 5px;
}

ul {
  list-style: none;
  padding: 0;
}

li {
  padding: 10px;
  background: #e3e3e3;
  margin-top: 10px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.done {
  background: #d1ffd1;
}