Why is calc not working with rem and px combined?

I tried the following style on a div but it is saying invalid css:

max-width: calc(24rem-13px);

The calc is using rem and px combined. If I remove the px part, then browser accepts the calc as valid style.

I am using latest Chrome.

>Solution :

You just need to add a space around the minus operator:

.test {
  background-color: gold;
  max-width: calc(24rem - 13px);
}

<div class="test">I have a max width</div>

It’s not working because without the space it could be interpreted as a negative value calc(24rem - -13px) for example