Fix button hover text visibility issue on login page
## Problem
On the login page (`/accounts/login/`), when hovering over secondary buttons (Login with OpenID, Login with Fedora, Create new user, Password reset), the text becomes invisible because it has the same color as the background.
## Root Cause
Theme CSS files (`green.css`, `red.css`, `clime.css`) contain overly broad `.btn:hover` selectors that override the specific button styling:
```css
.btn:hover,
.btn:active,
.btn:focus {
background: none;
border-color: #2d823e; /* theme color */
color: #2d823e; /* same as border - invisible on white background */
}
```
This causes:
- Background remains white (due to `background: none`)
- Text color changes to theme color (same as border)
- Result: invisible text on white background
## Expected Behavior
- Primary button (Login): Blue background with white text (works correctly)
- Secondary buttons: Should change from blue text on white background to white text on blue background on hover
## Solution
Add CSS overrides with higher specificity and `!important` declarations to ensure proper hover states:
- Override theme's `background: none` with `background: #335ecf !important`
- Force white text color on hover with `color: #fff !important`
- Cover all button contexts (`.button-group`, `.action-buttons`, etc.)
## Affected Components
- Login page buttons
- Any page using `.btn-secondary` class with theme CSS loaded
- All themes: green, red, clime
issue