Frontpage Menu and portfolio post thumbnails

Dear Support-Team,

I am currently working on a website with Enfold and several issues came up that I cannot solve. Hope you can help:

For you information, I adjusted the css a little. The whole custom CSS is as the following:

a:focus { background: #e2001a; color: black }

.grid-entry-title {
	font-weight: 700;
	color: white !important;
	vertical-align: middle;
	text-align: center;
	background-color: transparent !important;
	height: 30px;
	/*font-size: 1vh;*/
}

.grid-content {
	background-color: #e2001a !important;
	padding-left: 5px;
	padding-right: 5px;
}

.title_container .main-title {
	font-size: 24px;
	font-weight: 700;
}

.avia-menu-text {
	font-size: 18px;
}

1. The custom menu on my frontpage is broken.
Frontpage: http://birgit-monteiro.de/
Surprisingly it works on all other sites?!

2. On the following portfolio-sites the post-thumbnails are not displayed:
http://birgit-monteiro.de/portfolio-item/birgit-monteiro/
http://birgit-monteiro.de/portfolio-item/im-parlament/

working portfolio site for example:
http://birgit-monteiro.de/portfolio-item/fuer-menschen-mit-behinderung/

3. It seems to me that the changes I made on the site are not instantly visible. This seems not to be a browser related problem, because I already deleted the cache and it still remains…

I hope you can help…