The Navigator UI is unusable in high-brightness environments (Passthrough/MR) due to fixed background colors and lack of text shadows, violating standard legibility practices. To resolve this, expose existing CSS/React variables for backgroundColor (Hex codes), opacity (Alpha slider), and textShadow to the user. This can be achieved by implementing a low-effort change to the Master Style components, allowing users to customize the background color, opacity, and text shadow. Specifically, provide a Hex-Code Color Picker for the base color of the panel background, an Alpha/Opacity Slider for granular control over transparency, and a Text-Shadow Toggle/Value to ensure text remains crisp against the user-defined background. A global 'Reset to Default' button should also be included to mitigate user misconfiguration concerns.