JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.4.2/knockout-min.js"></script>
<h2 data-bind="style: {'--random-colour': randomColor, textDecoration: 'underline'}">This should receive a random text color.</h2>

CSS

h2 {
  /* default fall-back color: */
  --random-colour: #666;
  color: var(--random-colour);
}

JavaScript

var viewModel = function ViewModel() {
  this.randomColor = ko.computed(function() {
    // Random color thanks to @paul_irish
    return "#" + Math.floor(Math.random() * 16777215).toString(16);
  });
}();

ko.applyBindings(viewModel);