body {
  font-family: Arial, sans-serif;
  margin: 40px;
  background-color: #f6f9fc;
}

h1 {
  text-align: center;
  color: #2d3436;
}

form {
  display: flex;
  gap: 10px;
  justify-content: center;
  margin-bottom: 20px;
}

input, select, button {
  padding: 8px;
  border-radius: 5px;
  border: 1px solid #dfe6e9;
}

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

li {
  background: #fff;
  margin-bottom: 10px;
  padding: 12px;
  border-radius: 5px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.completed {
  text-decoration: line-through;
  color: #636e72;
}