body {
  font-family: Arial, sans-serif;
  background: #f2f2f2;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

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

h1 {
  text-align: center;
}

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

#taskInput {
  flex: 1;
  padding: 8px;
}

#addBtn {
  padding: 8px 12px;
  cursor: pointer;
}

ul {
  list-style: none;
  padding: 0;
  margin-top: 20px;
}

li {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: #eee;
  margin-bottom: 10px;
  padding: 8px;
  border-radius: 4px;
}

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

.task-buttons button {
  margin-left: 5px;
  cursor: pointer;
}