Default height of start page ( http://deploy.jtalks.org/forum/?lang=en# ) is more than 1080 pixels

By opening a start page of JCommune (http://deploy.jtalks.org/forum/?lang=en#) a default page height is too large (over 1080 pixels), it should be something like 800 or less pixels, because it is not so often users have a screen height more than 1080

See attached.