How can I change the Login Required page style?

Development
12

We added divs without classes into our customized login_required.welcome_message and then are using selectors like this the following to target that text:

.anon .contents.body-page div div {
}

.anon .contents.body-page div div:nth-of-type(2) {
}

For the rest of the page, we’re using overrides on the following selectors:

html.anon {
}

.anon .contents {
}

.anon .contents.body-page h1 a {
}

.anon .contents.body-page h3 {
}

.anon .contents.body-page h2 {
}

.anon .contents.body-page div p {
}

.anon .contents.body-page button {
}

.anon .contents.body-page button i {
}

.anon .contents.body-page {
}