I have the following CSS:
body {
width: calc(700px + 2 * 4rem);
}
.someclass {
margin: calc(2rem - 2px) 0;
}
When I run this through the W3C CSS validation, I get
Value Error : width Parse Error + 2 * 4rem)
Value Error : margin Parse Error - 2px) 0
What’s causing this? All the units I’m using in calc() are length units, and calc() should be able to handle it.
This is a known bug in w3 css validator:
来源：https://stackoverflow.com/questions/18035088/parse-errors-when-using-calc-with-rem-and-px