Ultimate Branding plugin css issue

I am trying to use Ultimate Branding plugin to edit my login page. Changing Logo and using css to change background image works perfectly. However, when I put more stuff into css, nothing changed. I was trying to make the login page looks better by changing the color of the box and text. Here is my code:
body.login {
background: url('http://www.xwism.com/wp-content/uploads/2016/07/sunset.jpg') no-repeat fixed center;
}

.login #login_error, .login .message {
padding: 12px;
margin-left: 0;
background-color: rgba(74, 74, 74, 0.77);
box-shadow: 0 1px 1px 0 rgba(0,0,0,.1);
}

body {
min-width: 0;
color: #ffffff;
font-family: "Open Sans",sans-serif;
font-size: 13px;
}

.login form {
margin-top: auto;
margin-left: auto;
padding: 26px 24px 46px;
background: rgba(60, 53, 53, 0.67);
box-shadow: 0 10px 40px rgba(255, 255, 255, 0.71);
}

.login label {
color: #dedede;
font-size: 14px;
}

.login #backtoblog a, .login #nav a {
text-decoration: none;
color: #d6d6d6;
}

Not sure it is my coding problem or the plugin issue. And also, my wordpress is muiltisite version, is that possible it forbid me from modifying the css?

Check my login page here:
http://www.xwism.com/wp-login.php?action=logout&_wpnonce=1e6b4eb02c