Generated by SassMeister.com.

input.scss

$border-width: 1px;
$pagination-border-width: $border-width;
$pagination-margin-start: ($pagination-border-width * -1);

@if $pagination-margin-start == (calc($pagination-border-width * -1)) {
  .selector {
    color: green;
  }
} @else {
  .selector {
    color: red;
  }
}

output.css

.selector {
  color: red;
}

settings.json

{
  "sass": {
    "compiler": "dart-sass/1.32.12",
    "extensions": {},
    "syntax": "SCSS",
    "outputStyle": "expanded"
  },
  "autoprefixer": false
}