Sass--运算

body{
    height: 800px;
    $smallBlockWidthAndHeight: 100px;

    .outside{
        background: gray;
        height: 500px;
        .smallBlock{
            width: $smallBlockWidthAndHeight;
            height: $smallBlockWidthAndHeight;
            background: red;
            display: inline-block;
            margin-left: 5px;
        }

        .resultBlock{
            width: $smallBlockWidthAndHeight / 2;
            height: $smallBlockWidthAndHeight / 2;
            background: blue;
            display: inline-block;
            margin-left: 5px;
        }
    }
}

body{
    // $str: "70px" + "80px";
    $str: 70px + 80px;
    .outside{
        width: 500px;
        height: 300px;
        background: gray;

        margin-left: $str;
    }
}

body .outside {
  width: 500px;
  height: 300px;
  background: gray;
  margin-left: 150px; }

body{
    $str: "70px" + "80px";
    .outside{
        width: 500px;
        height: 300px;
        background: gray;

        margin-left: $str;
    }
}

body .outside {
  width: 500px;
  height: 300px;
  background: gray;
  margin-left: "70px80px"; }

body{
    .outside{
        width: 500px;
        height: 300px;
        background: gray;

        &:after{
            content: "边距是：\"" + (70px + 80px) + "\"";
        }
    }
}

@charset "UTF-8";
body .outside {
  width: 500px;
  height: 300px;
  background: gray; }
  body .outside:after {
    content: ‘边距是："150px"‘; }