I have this CSS:

.read{
background-color: blue;
}

.unread{
background-color: green;
}

…and this HTML:

<p class="unread read">Hey</p>

The color of the element will be green.

My question is: Why? I can’t seem to find any reference saying that the order in the CSS file matters more than the order in the HTML file (where “read” appears last).