What must be true about CSS files when using Bootstrap?

The correct answer highlights that the CSS file should come after the Bootstrap CSS file. This is important because when you include your custom CSS file after Bootstrap, it allows your styles to override the default Bootstrap styles.

Bootstrap comes with its own set of predefined styles and components, which can be quite useful for rapid development. However, when you want to customize these styles, placing your CSS file after Bootstrap ensures that the browser reads your styles last. CSS applies styles in the order they are declared, so by positioning your own file after Bootstrap, any conflicting styles you define will take precedence over Bootstrap's styles.

Linking your CSS in the head section is also important for the correct rendering of the webpage, but the precise order of styles is what enables effective customization of Bootstrap components. This makes your styling more manageable and allows you to maintain the integrity of the Bootstrap framework while making necessary adjustments to fit your design needs.