looks strange.

but this would fix it
http://kriesi.at/documentation/enfold/custom-css-and-quick-css/

.iconlist_title {
    line-height: 1.3em !important;
}

The “go to top”-button in the bottom right corner has nothing to do with that.

It could be dissabled by using:

#scroll-top-link {
    display: none;
}

Also i dont see the header background changing and the onlything with a black background is the area that contains “agreements”, “payments”, “reminders” and the form to get future updates.

And thats because you have the following in your quick css:

.main_color {
background-color: #000000 !important;
}

thats really a mess, do you use any 3rd party plugins?

creating a thread: https://kriesi.at/support/forum/enfold/
Scroll down all the way to the bottom, there you can create a new thread.

For the other issue we’d need to see the website to see whats wrong

Looks fine for me. what are you expectations?
changing this:

html.html_boxed {
background-color: #ffffff !important;
}

into

`html.html_boxed {
background-color: #000000 !important;
}
will make the background black.
And i am sure it will work

Do you have a link to the site?
You might have to check the file permissions.
Maybe you dont have the right to write the files

Guess its the server the website is on.

You might want to check/increase the allocated memory http://www.bubbleindia.com/check-increase-php-memory-limit-wordpress/

you can increase the header height in the general styling options of enfold.
That should fix the problem.

Change the header height to 130px and your custom css should work again.

http://kriesi.at/documentation/enfold/turn-on-custom-css-field-for-all-alb-elements/
First solution was moving both (logo and menu) to the center.

Only moving menu to the left:
#header_main .main_menu {
position: relative ! important;
margin-left: 200px ! important;
}

Hmm, another option of yours that does not apply.

I think you really should check the file permissions

2 ideas: switch to stretched layout and then back to boxed layout and choose a background color

Also check your file permissions of the .css files. they should be 664

http://kriesi.at/documentation/enfold/turn-on-custom-css-field-for-all-alb-elements/

you can turn off the animation with

.avia-progress-bar div.progress .bar {
    animation: none;
}

To change the color of them you need to add (enter the color you want for each one):

.grey-bar .bar {
    background: #FFFFFF !important;
}
.blue-bar .bar {
    background: #FFFFFF !important;;
}
.green-bar .bar {
    background: #FFFFFF !important;;
}
.orange-bar .bar {
    background: #FFFFFF !important;;
}
.black-bar .bar {
    background: #FFFFFF !important;;
}
.red-bar .bar {
    background: #FFFFFF !important;;
}
.teal-bar .bar {
    background: #FFFFFF !important;;
}
.aqua-bar .bar {
    background: #FFFFFF !important;;
}
.purple-bar .bar {
    background: #FFFFFF !important;;
}
.pink-bar .bar {
    background: #FFFFFF !important;;
}
.silver-bar .bar {
    background:  #FFFFFF !important;;
}

see Devin’s answer.

There you can edit such things for the layer slider.

I guess your are looking for

.image-overlay {
 visibility: visible !important;
 }

But that should not be needed. do you have a link to you site with an example?
The overlay should be allways activated, even on small screens.

min-height is currenty set to 100px

http://kriesi.at/documentation/enfold/custom-css-and-quick-css/

.avia-section {
min-height: 0px;
}

site looks good so far, i’d suggest to look at the transparent menu since its hard to read it with some of the background images.
Maybe some decent text effects like a white shadow might help. would need some testing to see what looks good :)