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

body {
  font-family: Arial, sans-serif;
  background: #f3f4f6;
  display: flex;
  justify-content: center;
  padding: 2rem;
}

.container {
  background: #fff;
  padding: 2rem;
  border-radius: 10px;
  box-shadow: 0 4px 8px rgba(0,0,0,0.1);
  width: 100%;
  max-width: 400px;
}

h1 {
  text-align: center;
  margin-bottom: 1rem;
}

form {
  display: flex;
  margin-bottom: 1rem;
}

form input {
  flex: 1;
  padding: 0.6rem;
  border: 1px solid #ddd;
  border-radius: 5px;
}

form button {
  margin-left: 0.5rem;
  padding: 0.6rem 1rem;
  border: none;
  background: #2563eb;
  color: #fff;
  border-radius: 5px;
  cursor: pointer;
}

form button:hover {
  background: #1d4ed8;
}

ul {
  list-style: none;
}

li {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: #f9fafb;
  padding: 0.6rem;
  border: 1px solid #ddd;
  border-radius: 5px;
  margin-bottom: 0.5rem;
}

li.completed span {
  text-decoration: line-through;
  color: gray;
}

.actions button {
  margin-left: 0.5rem;
  padding: 0.3rem 0.6rem;
  border: none;
  cursor: pointer;
  border-radius: 5px;
}

.actions .edit {
  background: #10b981;
  color: white;
}

.actions .delete {
  background: #ef4444;
  color: white;
}

@media (max-width: 500px) {
  .container {
    width: 100%;
    padding: 1rem;
  }
}