Invalid calc() Expression

Co powoduje ten błąd

The calc() expression has missing spaces around operators, incompatible units, or invalid nesting. The + and - operators in calc() must be surrounded by whitespace.

Jak to naprawić

Add spaces around + and - operators: calc(100% - 20px). Ensure units are compatible. Check for proper parenthesis matching. Nest calc() correctly: calc(100% - calc(20px + 1em)).

div { width: calc(100%-20px); }