What's the Difference Between '.foo.bar' and '.foo .bar' in CSS Class Selectors?

Understanding the Difference in CSS Class Syntax: '.foo.bar' vs '.foo .bar'

In CSS, class names are used to apply styling to specific elements on a web page. However, there are two distinct syntaxes used for defining class names: one without a space and one with a space.

Syntax without a Space: .foo.bar

The syntax .foo.bar refers to an element that satisfies both the .foo and .bar classes. In other words, it selects elements that have both the .foo and .bar classes applied to them. For example, if you have the following CSS:

.foo {
  color: red;
}

.bar {
  background-color: blue;
}

And you apply the class .foo.bar to an element, that element will inherit the styling from both the .foo and .bar classes. It will have red text and a blue background.

Syntax with a Space: .foo .bar

In contrast, the syntax .foo .bar selects elements that have the .foo class and are descendants of elements that have the .bar class. For example, with the following CSS:

.foo {
  color: red;
}

.bar {
  background-color: blue;
}

If you apply the class .foo .bar to an element, it selects only elements with the .foo class that are inside elements with the .bar class. So, it would not select elements with only the .foo class or elements that are nested multiple levels deep within .bar elements.

Conclusion

Understanding the difference between these two CSS syntaxes is crucial for applying styling accurately to elements on a web page. The syntax without a space selects elements that have multiple classes applied, while the syntax with a space selects elements that have a specific class within a specific context.

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