Ho installato il sottotema di Zen 7.x 5 seguendo la procedura, ma andando a controllare i miei css, ne trovo di strani, e sopratutto non quelli descritti qui https://www.drupal.org/project/zen
Per esempio, 
io non ho il css blocks.css 
offtheme è il nome del sottotema:
public_html/sites/all/themes/offtheme/css/normalize-rtl.css
/public_html/sites/all/themes/offtheme/css/normalize.css
/public_html/sites/all/themes/offtheme/css/print.css
/public_html/sites/all/themes/offtheme/css/README.txt
/public_html/sites/all/themes/offtheme/css/styles-rtl.css
/public_html/sites/all/themes/offtheme/css/styles.css

/public_html/sites/all/themes/offtheme/css/components/misc-rtl.css
/public_html/sites/all/themes/offtheme/css/components/misc.css

/public_html/sites/all/themes/offtheme/css/layouts/fixed-rtl.css
/public_html/sites/all/themes/offtheme/css/layouts/fixed.css
/public_html/sites/all/themes/offtheme/css/layouts/responsive-rtl.css
/public_html/sites/all/themes/offtheme/css/layouts/responsive.css

Datemi una mano vi prego.