CSS Center Alignment

  Centering is one of the most common beginner problems.
  
  ## Types of centering
  - Text centering
  - Block centering
  - Vertical centering
  
  ## Center text
  ```css
  p {
    text-align: center;
  }
  ```
  
  ## Center block element
  ```css
  .box {
    width: 300px;
    margin: auto;
  }
  ```
  
  ## UI Visualization
  - Text appears in center
  - Box stays centered horizontally
  
  ## Real-world example
  - Login pages
  - Banners
  - Error messages
  
  ## Key rule
  Margin auto works only when width is defined.