Twenty Ten Child Menu Navigation change

Hello,
I have made changes to the #access code in my child theme stylesheet but the change will not stick. I see the changes initially but then when I visit the site later, it has reverted back to the default.

My website

Can anyone advise please?

#access a {
	color: #90e85d;
	display: block;
	line-height: 38px;
	padding: 0 36px;
	text-decoration: none;
}

Thanks