line-through style not working

I wanted to display the text of a button as line-through if it satisfies a certain condition. I have the following code in html:

<div class="col col-80" >
    <button  ng-class="{'fulfilled': item.itemStatus!='OPEN'}" class="row" ng-disabled="item.itemStatus!='OPEN'">{{item.displaydetail}} {{item.itemStatus}}</button> 
</div>

I have also defined the class in my css as follows:

.fulfilled {
text-decoration: line-through;
}

However, when I run the application, the button is disabled but the button text does not show the line-through. What could be the problem here?

PS. When I looked at the Element using Chrome inspect, I can see that the button class is correctly set to 'fulfilled'