Root partition size remains same after partition resize with gparted
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
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.