Use a css preprocessor, and define variables with the technical names but classes that end up in html should have descriptive names. Something like this:

  $accent_1_700: #e60000;
  $accent_2_900: #ff9999;

  @mixin button_border($color) {
    border: 1px solid $color;  
  }
  
  .alert-button {
    background-color: $accent_2_900;
    @include button_border($accent_1_700);  
  }

This makes your color palette defined explicitly and easy to change in one place, and makes which color on the palette you're using in a given context defined explicitly as well.