Custom CSS files you can add in overridden design.ini.append.php (per siteaccess or globally). Those files are loaded after default, so you can override existing styles.
ezwebin pre-view template calls full view template with parameter versionview_mode=true()
In your full view template you can check variable:
{if $versionview_mode}
preview
{else}
not preview
{/if}
hi Lukasz, thanks for the feedback but I can't seem to get the code to work, it doesn't seen to be able to tell the difference from a preview or edit page.