Are class names in CSS selectors case sensitive?

Class names in CSS selectors are case-sensitive. This means that when you specify a class name in HTML, you must ensure exact case matching when referencing it in CSS.

For example, suppose you have an element in your HTML:

html
<div class="Button">Click me</div>

If you use the following selector in CSS to set styles:

css
.button {
    background-color: blue;
}

This style will not be applied to <div class="Button"> because ".button" and "Button" do not match in case.

The correct selector should be:

css
.Button {
    background-color: blue;
}

This ensures that the styles are correctly applied to the corresponding HTML elements. Therefore, it is crucial to ensure that the case of class names in CSS matches exactly with those in HTML when writing CSS.