{\n  #{$property}: calc(#{$expression});\n}\n\n@mixin rotate($value) {\n  transform: rotate($value);\n}\n\n@mixin animation($animation) {\n  animation: $animation;\n}\n\n// Gradient background\n@mixin gradient($color: #F5F5F5, $start: #EEE, $stop: #FFF) {\n  background: $color;\n  background: -webkit-gradient(linear, left bottom, left top, color-stop(0, $start), color-stop(1, $stop));\n  background: -ms-linear-gradient(bottom, $start, $stop);\n  background: -moz-linear-gradient(center bottom, $start...