Size of block regions

Hi!

I am new at drupal and I am trying to figure out the size of the block regions. I have find the size of the sidebars but what is the maximum width for the other regions?

Where do I find this information? I have looked at the custom-style.css file but can only find the information down below:

}

/************************/
/* HEADER IMAGE ROTATOR */
/************************/
.himg #headimg {
background: #fff url(headerimg/rotate.php) no-repeat 100% 100%; /* rotates images in the headerimg folder */
border-bottom: 1px solid #eee;
}

Can somebody help me, please?

/Niclas