body {
  font-family: Arial, sans-serif;
  background: #f4f6f8;
  display: flex;
  justify-content: center;
  margin-top: 50px;
}

.container {
  background: white;
  padding: 20px;
  width: 350px;
  border-radius: 8px;
  box-shadow: 0 10px 20px rgba(0,0,0,0.1);
}

h1 {
  text-align: center;
}

.input-section {
  display: flex;
  gap: 10px;
}

input {
  flex: 1;
  padding: 8px;
}

button {
  padding: 8px 12px;
  cursor: pointer;
}

.filters {
  margin: 15px 0;
  display: flex;
  justify-content: space-between;
}

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

li {
  display: flex;
  justify-content: space-between;
  padding: 8px;
  margin-bottom: 5px;
  background: #eee;
  border-radius: 4px;
}

.completed {
  text-decoration: line-through;
  opacity: 0.6;
}