Root partition size remains same after partition resize with gparted
Solution 1:
It looks like gparted did extend the partition but not the file system. You will have to do that manually (ext4fs can be extended on a running system, even the / system).
Open a terminal and type
sudo resize2fs /dev/sda5
You will see something like "online-resize necessary" and then (after a few seconds) "the new size is ....".
Check the result with df -h once more - you should see the new size.