Clickable area for hyperlinks

Hi,

An 'a' HTML element with an 'href' attribute generates an hyperlink. 
When the link activation is pointer-based, where and how big exactly is 
the actionable area? How does this change for the various computed 
values of 'display' for the element? (eg. inline vs. block)

I could not find this in the HTML or CSS specs. In WeasyPrint we picked 
the margin/outer area of each principal box generated by the element. 
(We make this as high as 'line-height' for inline boxes.) This seems to 
match what browsers do.

I’m not sure where this *should* be defined: precise rectangles (for 
visual media) are more in CSS’s realm but as far as I know CSS has 
nothing on links. (The css3-hyperlinks module is marked abandoned and 
does not answer this question anyway.)

Regards,
-- 
Simon Sapin