* { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: Arial, sans-serif; background: #f5f5f5; display: flex; justify-content: center; align-items: center; height: 100vh; }
.todo-container { background: #fff; padding: 24px; border-radius: 6px; box-shadow: 0 4px 8px rgba(0,0,0,0.1); width: 100%; max-width: 400px; }
h1 { text-align: center; margin-bottom: 16px; color: #333; }
.input-group { display: flex; margin-bottom: 16px; }
#todo-input { flex: 1; padding: 8px 12px; border: 1px solid #ddd; border-radius: 4px; font-size: 16px; }
#add-btn { margin-left: 8px; padding: 8px 16px; border: none; background: #28a745; color: white; font-size: 16px; border-radius: 4px; cursor: pointer; }
#add-btn:hover { background: #218838; }
#todo-list { list-style: none; }
#todo-list li { padding: 10px; background: #fafafa; border-bottom: 1px solid #eee; display: flex; justify-content: space-between; align-items: center; cursor: pointer; }
#todo-list li.completed { text-decoration: line-through; color: #888; }
.delete-btn { background: transparent; border: none; color: #dc3545; font-size: 18px; cursor: pointer; }
.delete-btn:hover { color: #c82333; }