Pug // Condition in CSS in .pug partial file // https://stackoverflow.com/a/41618071/4415165

style.pug

style
  .
    .someclass1{
      font-size:10px;
    }
    .someclass2{
      font-size:10px;
    }
  if options.key1=='a'
    .
      .someclass3{
        font-size:10px;
      }
  else
    .
      .someclass3{
        font-size:8px;
      }
  .
    .someclass4{
      font-size:10px;
    }
    .someclass5{
      font-size:10px;
    }