<frequency-percentage>
<frequency-percentage> CSS 数据类型表示一个值，该值可以是 <frequency> 或 <percentage>。频率值（例如，人声的音高）目前并未在任何 CSS 属性中使用。
语法
<frequency-percentage> 的值可以是 <frequency> 或 <percentage>；有关其语法的详细信息，请参阅各自的参考页面。
描述
在 calc() 中使用
当 <frequency-percentage> 被指定为允许的类型时，这意味着百分比会解析为频率，因此可以在 calc() 表达式中使用。
正式语法
<frequency-percentage> =
<frequency> |
<percentage>
示例
有效的百分比值
90% Positive percentage +90% Positive percentage with leading + -90% Negative percentage — not valid for all properties that use percentages
无效的百分比值
90 % No space is allowed between the number and the unit
有效的频率值
12Hz Positive integer 4.3Hz Non-integer 14KhZ The unit is case-insensitive, though non-SI capitalization is not recommended. +0Hz Zero, with a leading + and a unit -0kHz Zero, with a leading - and a unit
无效的频率值
12.0 This is a <number>, not an <frequency>, because it is missing a unit. 7 Hz No space is allowed between the number and the unit. 0 Although unitless zero is an allowable <length>, it's an invalid <frequency>.
规范
| 规范 |
|---|
| CSS 值和单位模块第 4 级 # typedef-frequency-percentage |
浏览器兼容性
目前没有浏览器支持此功能。