[Pmwiki-users] (:noleft:) layout questions

Joachim Durchholz jo
Mon Dec 27 13:28:33 CST 2004


Hans Bracker wrote:
> 
> There is no such thing as 100% height.
 > [...]
 > You can make a div a certain size using width and height, but you need
 > to use units like px or em or such, not percentages.

Just for the record:

1) 100% height does exist in HTML, and it does even have its uses.

2) em is intended for measuring horizontal distances, ex for vertical ones.
Here's the list:
  unit Definition
   pt  Point       1/72 inch
   pc  Pica        12pt
   in  Inch        2.54 cm
   cm  Centimeter  1/100 m
   mm  Millimeter  1/1000 m
   px  Pixel
   em  width of small "m"
   ex  height of small "x"
   %   percentage (or parent or element itself)
Nothing will prevent you from using em vertically and ex horizontally; 
it just makes less sense than the other way round. (It might still make 
sense if you somehow manage to rotate text by 90 degrees, for example.)
Caveat: pixel sizes are defined in a highly artificial way. On Windows 
systems, a pixel is assumed to have 1/96 inch, on X Windows and MacOS, 
it's 1/72. On both systems, this holds regardless of real hardware 
characteristics.

Just trying to clean up misunderstandings before somebody gets misled by 
them, not sure whether this is relevant to the current discussion.

Regards,
Jo



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