units-per-em
SVG 2: 不再推荐使用该特性。虽然一些浏览器仍然支持它，但也许已从相关的 web 标准中移除，也许正准备移除或出于兼容性而保留。请尽量不要使用该特性，并更新现有的代码；参见本页面底部的兼容性表格以指导你作出决定。请注意，该特性随时可能无法正常工作。
The units-per-em attribute specifies the number of coordinate units on the "em square", an abstract square whose height is the intended distance between lines of type in the same type size. This is the size of the design grid on which glyphs (en-US) are laid out.
备注： This value is almost always necessary as nearly every other attribute requires the definition of a design grid.
Only one element is using this attribute: <font-face>
Usage notes
| Value | <number> |
|---|---|
| Default value | 1000 |
| Animatable | No |
<number>-
This value indicates the the number of coordinate units on the em square.
Specifications
| Specification |
|---|
| Scalable Vector Graphics (SVG) 1.1 (Second Edition) # FontFaceElementUnitsPerEmAttribute |
Browser compatibility
BCD tables only load in the browser