Your request is bad practice. Do not proceed.
While it is technically possible to do this, you should look into alternatives. Do not dynamically generate CSS files. They will be cached by your browsers, and dynamic changes will not be propagated.
Instead, make special-case classes that you can add to the HTML. Your CSS would become:
.proverb {
border: 0px solid blue;
margin-left: 0px;
}
.proverb.user-2 {
margin-left: 34px;
width: 250px !important;
margin-top: 6px;
}
In your HTML-generating code you can have:
<div class="proverb <?php if($suserid == 2) echo "user-2"; ?>"></div>
This will add the user-2 class if the user id is 2, and gives the same result as what you wanted in your example.
text/css.if ($suserid == 2) echo "<div class='proverb2'>user</div>";2. css:.proverb2 { ...<style> ... </style>tag in your HTML<head>).