- preg_replace: documentation ( source)
<?php
$css = "p {
border-radius: 5px;
transform: rotate(90deg);
}";
print preg_replace('~([;{])((?:linear-gradient|transition|transform|animation|border-radius|box-shadow)[^:]*):([^;}]+)(?=[;}])~s', '\1-webkit-\2:\3;-moz-\2:\3;-o-\2:\3;-html-\2:\3', $css);