[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 

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


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