"First HTML and CSS challenge "

Hello there anntvanntv, There are a lot of changes that would need to be made to this website.

1. Instead of assigning a class to the <main>, encase a <div> in the main and then you can assign a class of container
2. In your newly created div, encase a new div that will hold your <img> element and assign a class
3. Your links should not be in a list format. Instead you can encase them in a button element. Each button for a different link
4. The "challenge by...." sentence should be in the footer
5. For the styling try using the code below

*{
    margin : 0;
    padding: 0;
    box-sizing: border-box;
    max-width: 100%;
}


6. To style the body, add the following styles. You can try this for centering
```body {
           margin: 0;
           display: flex;
           justify-content: center;
          align-items: center;
          height: 100vh;
} 

7. You can try to read more or practice more on responsive web design.
[Freecodecamp] (https://www.freecodecamp.org/learn/2022/responsive-web-design/)