How can I make the subject section postbit like this?

[r4m1l]

Hello, NullForums
How can I make the subject section postbit like this???

How can I make the subject section like this in my own theme?

I want to do like this

 

[FateKid]

Hello, NullForums
How can I make the subject section postbit like this???

How can I make the subject section like this in my own theme?

I want to do like this

We actually just recoded our website this way!
It will take time and programming experience. We've edited and changed 99% of templates in the backend.