Oracle Enterprise Manager High-Contrast UI Theme: Missing Configuration Option for Accessibility Compliance

Goal

Enable a built-in high-contrast UI mode in Oracle Enterprise Manager (EM) to meet WCAG 2.1 accessibility requirements for users with visual impairments.

Constraints and Uncertainty

EM's current UI customization is limited to logo replacement and basic color-scheme changes; there is no documented configuration parameter, REST endpoint, or plug-in mechanism to activate a high-contrast theme or scalable font sizing. Oracle's on-premises accessibility guidelines reference WCAG 2.1, yet the generated EM pages lack ARIA-compliant markup and a native high-contrast option, forcing reliance on external browser extensions that cannot modify EM's internal frames. Feature parity across EM versions (12c, 13c, 13.5) is unclear, and any custom CSS injection requires EM administrator privileges with potential cross-user impact.

Questions

1. Is there an undocumented EM system property or repository setting that exposes a high-contrast theme without modifying core EM files?
2. Can a custom plug-in or skin be deployed through the EM Plugin Framework to provide WCAG-compliant contrast ratios and font scaling while remaining supported across patch sets?
3. What is the earliest EM release version that includes a native accessibility-mode toggle, if any?