reference specific value inside of a class?

i’m trying to reference one part of a class in order to calculate something in another part of the code. i only want to reference the dimensions, nothing else. below, you will see cobra’s dimensional information is blank. i’m choosing arbitrary numbers and calculations – just trying to make it slightly "complicated" enough to explain a bit more. i hope this makes sense:

• i want cobra’s width to equal viper’s width divided by 2.
• i want cobra’s height to equal viper’s height exactly.
• i want to be able to only change viper’s information and have
  cobra automatically update because it references viper.

.viper
 {
    width: calc((100px - 50px) * 3) / 2);
    height: 200px;
    font-family: garamond;
    font-color: black;

 }

.cobra
  {
    width:
    height:
    font-family: georgia;
    font-color: blue;
  }

>Solution :

If you are trying to accomplish this with JUST CSS, this can be accomplished quite easily using CSS variables.

First declare your viper’s width and height as a basis for a snake:

 :root{
  --viper-width: calc((100px - 50px) * 3) / 2);
  --viper-height: 200px;
 }

Then you give this variable to the equivalent properties of your snakes that you wish to modify in relation to the viper.

.cobra{
  width: calc(var(--viper-width) / 2);
  height: var(--viper-height);
  font-family: georgia;
  font-color: blue;
}

Then, any time you change your --viper-width and --viper-height variables, your .cobra will adjust accordingly.