``++calc++`` is a CSS3 function that provides the possibility to do simple math in CSS (add, subtract, divide, multiply). Without spaces around operators, ``++calc++`` will have no effect.
More precisely, before an operator, there must be a single whitespace or a newline plus indentation. After an operator, there must be a single whitespace or a newline.
== Noncompliant Code Example
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#div1 {
position: absolute;
width: calc(100%- 100px); /* Noncompliant; no space after the % sign */
