[horde] css caching problems when upgrading horde

[dev at stean.ch]

hello all,

i recently updated from horde 3.1.4 to 3.3, and imp was
4.1.4 to 4.3. soon most users complained about strange
rendering issues when using horde. which was nothing but
that the old css files where still in theyr browser caches.

i am not at all experienced with the caching mechanisms of
horde, or if it would be the standart web caching mechanisms.
but would like to avoid such troubles for future updates.

is there a way to tell the browsers that they should also
reload the updated css files, without the need that each user,
quite some, has to empty the cache of the browser by itself?

thanks for any hint

stephan