How to make images scaled down?

[miriam-z]

Can't seem to find image scaling down? part of my React component: Changing the 25x25? to other values does not seem to have any affect?

return (
        <div>
            <ul>
                {arrays.map(array =>
                    <li key={array.id}>
                        <div><img src={array.author.avatarUrl} alt="" className="img-thumbnail"
                                  data-src="holder.js/**25x25**?auto=yes" id="new"/></div>
                        <div>{array.title} {array.tags}</div>
                        <div>Created on {array.timestamp} by {array.author.username}</div>
                        <div>{array.body}</div>
                    </li>)}
            </ul>
        </div>

[imsky]

could you please create a jsfiddle/codepen or another way to reproduce this issue?

a screenshot would also be a good start to understanding what the problem is.