问题描述
我学习了CSS函数calc（）和它的真棒。我试着使用它：
I learned about the CSS function calc() and its awesome. I tried to use it like:
#abc{width:calc(100%-20px)}
但是这个函数的问题是它不工作。我测试了这个代码IE9和Safari并且没有工作。
But the problem with this function is that it doesn't work. I tested this code IE9 and Safari and it didn't work.
为什么不工作？
推荐答案
运算符 - 必须用空格包围：
The operator "-" must be surrounded by spaces:
#abc{width:calc(100% - 20px)}
引用：注意： +和 - 运算符必须始终包含空格。例如，calc的操作数（50％-8px）将被解析为百分比，接着是负长度，无效的表达式，而calc（50％-8px）的操作数是百分比，其后是负号和长度。
Quoting MDN info on calc(): "Note: The + and - operators must always be surrounded by whitespace. The operand of calc(50% -8px) for instance will be parsed as a percentage followed by a negative length, an invalid expression, while the operand of calc(50% - 8px) is a percentage followed by a minus sign and a length."
关于此的正式声明在的CSS值和单元模块第3级CR。
The formal statement on this is in clause 8.1.1 of the CSS Values and Units Module Level 3 CR.
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