MDN指出您可以使用 1-4 之间的数字作为长度属性,但它没有任何效果。
这有什么原因吗?
p {
font-size: 0.85em;
background-color: red;
border-radius: 4;
}
<p>Alice was beginning to get very tired of sitting by her sister on the bank, and of having nothing to do: once or twice she had peeped into the book her sister was reading, but it had no pictures or conversations in it, 'and what is the use of a book,'
thought Alice 'without pictures or conversations?'</p>
最佳答案
Note: The points indicated by Thieu Nguyen are valid. I am adding a separate answer because I think your problem is due to the interpretation (wrong) of the formal syntax and because I'm not comfortable forcing my content into another answer.
MDN page for border-radius
没有任何地方说明我们可以使用 1-4 之间的数字作为长度值。事实上,CSS 中的所有长度值都必须后跟一个单位,唯一的异常(exception)是 0。
以下是 CSS Spec for Length Units 的摘录:(强调是我的)
The format of a length value is an optional sign character ('+' or '-', with '+' being the default) immediately followed by a number (with or without a decimal point) immediately followed by a unit identifier (a two-letter abbreviation). After a '0' number, the unit identifier is optional.
基于your comment ,我感觉你混淆了 {1,4}
在正式语法中是无单位值。
[ <length> | <percentage> ]{1,4} [ / [ <length> | <percentage> ]{1,4} ]?
但它们不是无单位的值。它就像正则表达式中的,其中 [a]{x,y}
表示 a 的最少出现 x 次和最多出现 y 次。因此,以下是应如何解释正式语法:
-
[ <length> | <percentage> ]
- 表示长度或百分比可以是值。 -
{1,4}
- 表示前一个实体必须至少出现一次,最多出现四次。也就是说,该值应至少为一个长度或百分比,最大为四个长度或百分比。 -
[ / [ <length> | <percentage> ]{1,4} ]?
- 与上面类似,但末尾的问号表示该位是可选。即/
其后面的长度或百分比值是可选的。如果提供,它们将用作垂直边框半径,如果没有,它们将与水平半径相同。
关于html - 使用单独数字(无单位值)的 CSS3 border-radius 不起作用,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/35930208/