CSS for main menu follows on to drop-down submenu

Hello,
Thanks for a great theme. I am using it to change a clients site to a responsive site (locally at this stage).
At this stage I have run into some problems with the main menu/drop down. I’ll try to explain as good as I can what I want to achieve and what’s going wrong. I’m using the header with logo left and menu below. I’ll add the css used at the end.
1) The main menu (first level) should be black letters with no background. When hovered it changes font color to white and adds a black background with rounded top right and left corners. And this should also remain when clicked (active state). This I have managed to achieve and it also works. Here a link to the present site to illustrate: http://www.easyblast.fi/index.php/blastring

2) The sub menu (drop down) should have white background with blue font (#032366). When hovered (and also active state) it should change the menu item font color to white and background color to green (#55a51c).

Now to the problems:
A) When hovering the the drop down menu items the font color and background color changes as they should, BUT the rounded top left/right corners from the main level follows down to the sub menu, which it should not.
B) When you are on a sub page, the main (parent) level menu item is no longer highlighted. And on the drop down sub menu “active” page is only the menu word(s) highlighted and not the whole menu item.
C) Also when you hover on a main level to get the drop down visible and then moves the cursor down on the drop down, the background hover state disappears from the main level item, which as the font color is white with white background means that it gets invisible.

Phew, this was quite a long one, but here is still the css (I started from a snippet found on the forum) for you to look at:
– – – –
/* idle */
.avia-menu-text{color: Black; }
.sub-menu .avia-menu-text {color: #032366!important; }

/* hover */
#top .main_menu ul:first-child>li a:hover {
color: #FFFFFF;
background-color: #000000;
text-decoration: none;
-webkit-border-top-left-radius: 6px;
-webkit-border-top-right-radius: 6px;
-moz-border-radius-topleft: 6px;
-moz-border-radius-topright: 6px;
border-top-left-radius: 6px;
border-top-right-radius: 6px;
}

li.menu-item:hover .avia-menu-text {color: White; }

.sub-menu li.menu-item:hover .avia-menu-text{
color: white!important;
-webkit-border-top-left-radius: 0px;
-webkit-border-top-right-radius: 0px;
-moz-border-radius-topleft: 0px;
-moz-border-radius-topright: 0px;
border-top-left-radius: 0px;
border-top-right-radius: 0px;
}

/* active */
.main_menu .current-menu-item {
color: #FFFFFF!important;
background-color: #000000!important;
margin-right: 10px;
-webkit-border-top-left-radius: 6px;
-webkit-border-top-right-radius: 6px;
-moz-border-radius-topleft: 6px;
-moz-border-radius-topright: 6px;
border-top-left-radius: 6px;
border-top-right-radius: 6px;
}

.main_menu .current-menu-item span.avia-menu-text {color: #FFFFFF!important; }

.sub-menu .current-menu-item span.avia-menu-text {background-color: #55a51c!important; }
– – – –
I really hope that you are able to help me with this one.

Cheers