update global-header.css to fix bug in header links in mobile
update global-header.css to fix bug in header links in mobile

schumann-library/libguides2-customizations,schumann-library/libguides2-customizations,Adam-Shire-WIT/libguides2-customizations,adamshire/libguides2-customizations,Adam-Shire-WIT/libguides2-customizations