The megamenu is working ok but not on the checkout page. On that page the menu is invisible unless you hoover over it with the mouse !
The site is http://www.jukebox.skyberatedev.nl
To fix this issue, please follow steps below:
Open the file: app/design/frontend/Ubertheme/megamall/Ubertheme_UbMegaMenu/web/css/source/module/horizontal.less, navigate to line 1153 and change as follows:
Once done please re-compile LESS -> CSS as instructed to you before. For your convenience, I include the steps below:
You should back up your site first. Once done, you access your server via SSH and navigate to your Magento 2 folder, then run the following commands one by one:
Step 1: php bin/magento maintenance:enable
Step 2: rm -rf var/di/* var/generation/* var/cache/* var/log/* var/page_cache/* var/session/* var/view_preprocessed/* pub/static/frontend/Ubertheme/megamall/*
Step 3: php bin/magento setup:static-content:deploy -t Ubertheme/megamall -f (Make sure you are using developer (or default) mode)
Step 4: php bin/magento cache:flush
step 5: php bin/magento maintenance:disable
Step 6: clear your browser cache
Hope that helps.