I'm using a current version of Firefox.
Here is the offending code in a CSS of a plugin:
/*
.rotate {
white-space: nowrap;
-webkit-transform-origin: 65px 60px;
-moz-transform-origin: 65px 60px;
-o-transform-origin: 65px 60px;
-ms-transform-origin: 65px 60px;
transform-origin: 65px 60px;
-moz-transform: rotate(-90.0deg); /* FF3.5+ */
-o-transform: rotate(-90.0deg); /* Opera 10.5 */
-webkit-transform: rotate(-90.0deg); /* Saf3.1+, Chrome */
filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=0.083); /* IE6,IE7 */
-ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=0.083)"; /* IE8 */
}
.vertical-text {
display: inline-block;
overflow: hidden;
width: 1.5em;
}
.vertical-text__inner {
display: inline-block;
white-space: nowrap;
line-height: 1.5;
transform: translate(0,100%) rotate(-90deg);
transform-origin: 0 0;
}
.vertical-text__inner:after {
content: "";
display: block;
margin: -1.5em 0 100%;
}
*/
.database2-disabled
{
font-style: italic;
text-align: center;
margin: 1em;
}
As you can see the commenting is wrong, which leads into illegal CSS. Try this for yourself and you will find that LESS-parser does not complain about, but produce the above CSS-result.