您好，我有以下问题：
“在定义CSS颜色时需要at-rule或选择器。”
我使用VS代码，我已经检查了CSS在https://jigsaw.w3.org/css-validator/validator#css
我不知道这里有什么问题！

/* Color Variables */
$red: red;
$green: green;
$orange: orange;
$blue: blue;
$purple: purple;
$white: white;
$black: black;
$bg: /* #eff3f6 */ #e3e5e6;
$darkgray-blue: #354052;
$lightgray-blue: #7f8fa4;

/* Styles */
body {
  background: $bg;
  font-family: 'Roboto', sans-serif;
  letter-spacing: 1px;
}

.text-red {color: $red !important;}
.text-green {color: $green !important;}
.text-orange {color: $orange !important;}
.text-blue {color: $blue !important;}

/* buttons */
.btn-red {
  background: $red;
  color: $white;
  font-size: xx-small;
  &:hover, &:focus {
    background: darken($red, 8%);
    color: white;
  }