What are valid values for CSS Property “padding-right-ltr-source”?

问题

I am trying to solve a box padding problem in Firefox. When I expanded the "padding" property of the affected span element, I saw there is a property called "padding-right-ltr-source" with value "physical":

>padding: 0px 15px;
    padding-top: 0px;
    padding-right-value: 15px;
    padding-bottom: 0px;
    padding-left-value: 15px;
    padding-left-ltr-source: physical;
    padding-left-rtl-source: physical;
    padding-right-ltr-source: physical;
    padding-right-rtl-source: physical;

What are the other possible values for these properties?

EDIT: I ended up using transparent border instead of padding, since it has consistant behaviour across the browsers.

回答1:

This property has two possible values: "physical" and "logical". It's also an internal property that you can't set directly in a stylesheet. It's used to implement the interactions of things like a stylesheet setting both padding-start and padding-right in a single rule, on elements with different directionalities... The former sets padding-left-ltr-source: logical and padding-right-rtl-source: logical while the latter sets padding-right-ltr-source: physical and padding-right-rtl-source: physical.

来源：https://stackoverflow.com/questions/21166787/what-are-valid-values-for-css-property-padding-right-ltr-source