Try with:
#fadein {
-webkit-animation-fill-mode: forwards; /* Chrome 16+, Safari 4+ */
-moz-animation-fill-mode: forwards; /* FF 5+ */
-o-animation-fill-mode: forwards; /* Not implemented yet */
-ms-animation-fill-mode: forwards; /* IE 10+ */
animation-fill-mode: forwards; /* When the spec is finished */
}