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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: #f5f5f5;
  min-height: 100vh;
  padding: 40px 20px;
}

.container {
  max-width: 500px;
  margin: 0 auto;
  background: white;
  padding: 30px;
  border-radius: 10px;
  box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

h1 {
  text-align: center;
  color: #333;
  margin-bottom: 30px;
}

#todo-form {
  display: flex;
  gap: 10px;
  margin-bottom: 20px;
}

#todo-input {
  flex: 1;
  padding: 12px;
  border: 2px solid #ddd;
  border-radius: 6px;
  font-size: 16px;
}

#todo-input:focus {
  outline: none;
  border-color: #007bff;
}

#todo-form button {
  padding: 12px 24px;
  background: #007bff;
  color: white;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  font-size: 16px;
}

#todo-form button:hover {
  background: #0056b3;
}

#todo-list {
  list-style: none;
}

.todo-item {
  display: flex;
  align-items: center;
  padding: 15px;
  border-bottom: 1px solid #eee;
  gap: 10px;
}

.todo-item:last-child {
  border-bottom: none;
}

.todo-item input[type="checkbox"] {
  width: 20px;
  height: 20px;
  cursor: pointer;
}

.todo-item span {
  flex: 1;
  font-size: 16px;
}

.todo-item.completed span {
  text-decoration: line-through;
  color: #999;
}

.todo-item .delete-btn {
  background: #dc3545;
  color: white;
  border: none;
  padding: 6px 12px;
  border-radius: 4px;
  cursor: pointer;
}

.todo-item .delete-btn:hover {
  background: #c82333;
}