Check out example codes for "css multiple classes". It will help you in understanding the concepts better.
Code Example 1
To specify multiple classes, separate the class names with a space,
e.g. <span class="classA classB">.
This allows you to combine several CSS classes for one HTML element.
Code Example 2
//HTML Code
<div class = 'firstClass secondClass'></div>
//CSS Code
.firstClass.secondClass {
}
Code Example 3
<div class="a-class another-class"></div>
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