Error message

variable @blue is undefined in file /var/www/vhosts/pyhtaa.helga.loopy.fi/httpdocs/themes/pyhtaa/less/frontpage.less in frontpage.less on line 55, column 35 53| width:100%; 54| height:auto; 55| border-left:8px solid @blue; 56| img 57| { 58| width:100%;