I have re-installed PS V1.7.6.8 and switched to PHP v.7.3. This resolved the CSS problem, thanks for tip.
However, I am faced with another problem upon attempting to updated modules as instructed by the system. If I upgrade I 1st module get an error “ Error! Could not perform action update for module undefined” then I get “HTTP ERROR 500” UPON REFRESHING THE PAGE. If I refresh again and attempt to upgrade the same module again, it gives me successful upgrade.
If I do this process to each module, I end up upgrading all modules requiering an update.
Now if I do chnages within the Module Manager, I get “HTTP ERROR 500” then I need to refresh and attempt again