在BEM CSS中能否嵌套块/元素到修饰符内？写法合规性咨询

Great question—let’s break this down specifically for your navigation scenario, since that’s where you’re applying this pattern.

Short answer: Yes, this is 100% compliant with BEM methodology #

Your approach of using .navigation--opened .navigation__list and similar selectors is totally aligned with BEM’s core principles. Here’s why:

BEM basics recap #

BEM revolves around three core concepts:

• Block: The standalone, reusable component (your navigation here)
• Element: A part of the block that can’t exist independently of it (like navigation__list, navigation__item)
• Modifier: A flag on a block/element that changes its appearance, behavior, or state (your navigation--opened toggle state)

When you apply a modifier to a block, it’s meant to signal a global state change for the entire component. Styling the block’s elements based on this modifier is exactly how BEM intends you to handle component-wide state shifts.

Why this works perfectly for your navigation #

Your navigation--opened class tells the browser the entire navigation is in an "expanded" state. Rather than cluttering your markup with individual modifiers for every element (like navigation__list--opened or navigation__item--opened—which would be redundant and harder to maintain), using the block’s modifier to target its elements keeps your code clean and logically tied to the component’s overall state.

This approach also keeps your selectors flat (no deep nesting like .navigation .navigation__list .navigation__item), which is a key BEM best practice for performance and long-term maintainability.

Alternative valid approaches (for edge cases) #

While your current method is ideal for this hamburger menu scenario, there are other BEM-compliant ways to handle state if your use case evolves:

• If only one element needed to change state independently of the block, you could add a modifier directly to that element (e.g., navigation__list--visible)
• For more complex state combinations, you might stack multiple block modifiers (e.g., navigation--opened navigation--mobile)

But for your toggleable menu, sticking with .navigation--opened to target all child elements is the most efficient and BEM-friendly choice.

内容的提问来源于stack exchange，提问作者BartTux