I need some explanation for comments.

[dotJoon]

/* commented backslash hack v2 \*/ 
html, body{height:100%;} 
/* end hack */

The above is from Paul O' B's code.

What does " commented backslash hack V2 \* " mean?
What does " end hack " mean?

I don't understand the word "hack" here.
(I am not a native speaker of English.)

[maxor]

The use of hack in this context means to work around or by-pass some functionality that is missing in a certain web browser.

It's a hack because it solves the problem, but not in the best way possible.

Here are more examples of using the word in a similar context:
"I could not get the pieces of this bike to fit, so I hacked it together with some duct tape"

"Internet explorer does not like my css, so I had to add a hack to it so that it would work"

"I cannot play international games on my playstation, but there is a hack that lets me"

"This table was put together poorly, looks like it was hacked together"

Basically you use a hack to overcome some problem, usually in a crude and simplistic way.

[dotJoon]

"I could not get the pieces of this bike to fit, so I hacked it together with some duct tape"

"Internet explorer does not like my css, so I had to add a hack to it so that it would work"

"I cannot play international games on my playstation, but there is a hack that lets me"

"This table was put together poorly, looks like it was hacked together"

Thanks for your explanation and the example code above.
(English is sitll codes for me.)

[maxor]

Thanks for your explanation and the example code above.
(English is sitll codes for me.)

Sounds like you're doing well, I couldn't even spot a Korean character if I tried.