Trying to add a border

Tell us what’s happening:
.thick-green-border {
border-color: green;
border-width: 10px;
border-style: solid;
I have this code m trying to add a border, but it does not work.
I even created a class for this with this code “

What you have should work if your element has the class thick-green-border… (Example:

<div class="thick-green-border"></div>

You can also try putting it all on one line like:
border: 10px solid green;