AWS ECS Task: Why is the container having more CPU core and Memory than what I specified in Task Definition?

Question

I started a stand-alone Task in AWS ECS;

In the Task Definition, I specified 0.5 vCPU and 1 GB Memory

However, when I ssh into the running task container and execute htop to inspect:

I see 3.62GB of memory. Why?

And why is 0.5 vCPU translated into 2 CPU cores in the container? Why would it not be 1 cpu core of 4 CPU cores?