I’ve got the following error message when trying to preview a skin on a just installed theme.
The problem is solved saving theme settings for the first time, probably you should save theme defaults on theme activation if they don’t exist yet.
Fatal error: Uncaught exception ‘Exception’ with message 'parse error: failed at `@heading-weight:;@logo-font:"", sans-serif;@logo-weight:;@logo-size:px;@body-bg-image:none;@body-bg-repeat:no-repeat;@body-bg-position:0 0;@body-bg-attachment:scroll;@body-bg-size:auto;@body-bg-color:#f2f2f2;@body-bg-color-2:darken(#f2f2f2, 5%);@body-fg-color:#000000;@border-color:darken(#ffffff, 10%);@border-color-2:darken(#ffffff, 20%);@content-bg-color:#ffffff;@content-bg-color-2:darken(#ffffff, 1%);@content-bg-color-3:darken(#ffffff, 3%);@content-fg-color:#000000;@top-bar-bg-color:#326796;@top-bar-fg-color:#ffffff;@top-bar-bg-grad:0;@header-bg-color:#326796;@header-fg-color:#ffffff;@header-bg-grad:10;@fixed-header-bg-color:#326796;@fixed-header-fg-color:#ffffff;@fixed-header-accent-color:#ffffff;@nav-bg-color:#428aca;@nav-fg-color:#ffffff;@nav-bg-grad:0;@mobile-nav-bg-color:lighten(#326796, 10%);@mobile-nav-fg-color:#ffffff;@footer-widgets-bg-color:#326796;@footer-widgets-fg-color:#ffffff;@footer-bg-color:#428aca;@footer-fg-color:#ffffff in /home/sor/webapps/wp_sor/wp-content/themes/fl-automator/classes/lessc.inc.php on line 3460