Improved dark mode rendering quality.

• Fixed custom checkboxes and radio buttons that appeared checked while still unchecked. Sign-up forms where "Next" or "Agree" seemed unresponsive now work as expected.
• Toggle ON/OFF, selected tabs, and checked states now keep their accent colors.
• Fixed large photos turning black on brand and fashion sites.
• Fixed light-themed sites being mistaken for native dark mode, which disabled dark mode entirely.
• Fixed pages on sites that rely heavily on CSS variables staying white with light, unreadable text.
• Stronger ad blocking on ad-heavy pages such as news aggregator and matome blog sites.