[css-text] allow line-height to accept aspect-ratio style values

[scottkellum]

Unitless line-height is generally accepted as the best type of value for line-height, however this can sometimes be confusing for people to calculate from pixel-based mockups.

Proposal

Allow line-height to accept ratio formatted values similar to aspect-ratio. This would let authors easily convert pixel based values to numbers without the need for calc. So if a mockup has a font size of 16px and a line height of 20px, the CSS author would be able to write line-height: 20 / 16 instead of line-height: calc(20 / 16) or doing the math to write line-height: 1.25.

[Crissov]

This syntax most likely wouldn’t work with the font shorthand property, wherein: <font-size> / <line-height> <font-family>.

[scottkellum]

@Crissov yeah I wasn't expecting it to work there as that syntax is so specific in formatting.

[fantasai]

I really don't think that complicating the line-height syntax in order to avoid writing calc() around your calculation is appropriate here...