Hi Lê Đức Long
Here are a few suggestions for improvement your code
HTML
Use semantic HTML elements:
Instead of using a div for everything, use semantic HTML elements such as header, nav, main, section, etc., to better describe the structure and purpose of your content.
CSS
Consistent naming convention:
Consider using a consistent naming convention, such as BEM (Block, Element, Modifier), to keep your CSS organized and avoid naming conflicts.
Reusable classes:
Create reusable classes for styles that are used multiple times in your code. This will make it easier to maintain and update your styles.
Use CSS variables:
Consider using CSS variables to store values that are used multiple times in your code, as this makes it easier to maintain and update your styles.
Minimize the use of hard-coded values:
Instead of hard-coding values, consider using relative units such as em, rem, vw, vh, etc., to make your styles more flexible and adaptable to different devices and screen sizes.
Happy Coding