Adding CSS to variables.less breaks the compiler

Hi,

I have added some CSS to variables.less as i want to use less variables in my CSS code.

When i run the Less compiler with the “preserve customisations” it goes to a white screen and does nothing.

Some example CSS – nothing too crazy…

nav ul { float: left;
    margin: 0;
    padding: 0;
    width: 100%;}
nav ul li {display:inline-block; width:25%; color:@grayDarker; border-bottom:8px solid @blue; margin-left:-4px;}
nav ul li:hover {display:inline-block; width:25%; color:@grayDarker; border-bottom:8px solid @yellow; margin-left:-4px;}
nav ul li a {color:@grayDarker; font-size:17px; display:block; padding:0 0 5px 0;}
nav ul li a:hover {color:@grayDarker; font-size:17px; display:block; text-decoration:none;}
.header {margin-top:30px;}

Any help appreciated.

Rob

https://wordpress.org/plugins/wordpress-bootstrap-css/