The issue you're experiencing with pale artifacts around the orange letters in Firefox may be related to how the browser handles font rendering and anti-aliasing. You can try applying the font-smooth property in your quordle CSS.
body {
-webkit-font-smoothing: antialiased; /* For Safari */
-moz-osx-font-smoothing: grayscale; /* For Firefox */
font-smooth: always; /* General setting */
}
Go to Options > General > Performance and uncheck "Use recommended performance settings." Then, uncheck "Use hardware acceleration when available."