How to style icon color, size, and shadow of Font Awesome Icons

Given that they're simply fonts, then you should be able to style them as fonts:

#elementID {
    color: #fff;
    text-shadow: 1px 1px 1px #ccc;
    font-size: 1.5em;
}

You can also just add style inline:

<i class="icon-ok-sign" style="color:green"></i>

<i class="icon-warning-sign" style="color:red"></i>

If you are using Bootstrap at the same time, you can use:

<i class="fa fa-check-circle-o fa-5x text-success" ></i>

Otherwise:

<i class="fa fa-check-circle-o fa-5x" style="color:green"></i>

Related