Hide post date and author from pages (not posts)

I tried (per other post) adding to custom.css:

.blog-post-date-area
{
display:none;
}

.blog-post-lg
{
display:none;
}

But that prevents the date from showing on blog posts (where I want to see it) as well as pages. Is there code I can add to custom.css to prevent the date and author from showing up on pages only?