CSS

css multiple classes

//HTML Code
<div class = 'firstClass secondClass'></div>

//CSS Code
.firstClass.secondClass {
  
}

css multiple classes same rule

.bucket1, .bucket2, .bucket3 {
}

.bucket4, .bucket5, .bucket6 {
}

css assign multiple classes to one element

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.