There are three major problems with using ID for style design: first, the ID selector is too specific and makes it difficult to overwrite; second, the ID cannot be reused to force code duplication or structural compromise; finally, modern development has better alternatives. The high specificity of ID makes style modification difficult, easily causing redundant code and!important abuse; the limitation of ID uniqueness in HTML hinders style reuse, while class selectors naturally support multi-element reuse; currently available tools such as BEM, CSS-in-JS and Tailwind provide greater flexibility and maintainability. Although IDs are useful in anchor linking or JavaScript positioning, they should be avoided for style design to ensure scalability and consistency of CSS.

Using IDs for styling might seem straightforward at first, but it can lead to some real headaches down the line. The main issue is that IDs are too specific and rigid for most styling needs. While they get the job done in simple cases, they tend to cause more problems than they solve in larger or more complex projects.

ID Selectors Are Overly Specific

One of the biggest downsides of using IDs in CSS is their high specificity. An ID selector like #header has a much higher priority than classes or element selectors. This means if you try to override styles later—say with a theme or responsive layout—you'll find yourself fighting against your own code.

• You may end up writing even more specific selectors just to make changes.
• It becomes tempting to use !important , which leads to messy, hard-to-maintain code.

Instead of relying on IDs, using class-based selectors give you more flexibility and makes your CSS easier to manage.

IDs Can't Be Reused

HTML IDs are meant to be unique per page. That's great for JavaScript hooks or anchor links, but not so great for styling. If you define a style using an ID, you can't apply it to multiple elements without duplicating code or changing your markup.

For example:

• You want two buttons that look the same.
• One uses #submit-button , the other needs the same look but isn't a submit button.

Suddenly, you either write duplicate styles or change how you structure your HTML just for styling purposes. Classes avoid this problem entirely by design.

Better Alternatives Exist

In modern web development, we have better tools for organizing styles:

• Classes let you reuse styles freely and combine them in different ways.
• BEM or similar naming methods help keep your class names meaningful without conflicts.
• CSS-in-JS solutions or utility-first frameworks like Tailwind take reusability even further.

IDs still have their place—for things like fragment identifiers or JavaScript targeting—but styling shouldn't be one of them.

Avoiding IDs for styling might feel like a small detail, but it helps keep your CSS scalable, predictable, and easier to work with over time. Not a flashy rule, but a solid one.

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